Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim status: claims 1-2, 9, 11-14, and 18-20 are pending in this Office Action.
Examiner note: Spec [0081] the detection apparatus 230 comprises an optical receiver, D1, such as a single photon avalanche photodetector, SPD, and processing circuitry configured to determine whether the detected photon is delayed relative to a reference time and to determine the qubit according to the determined time delay. So system claims comprise hardware.
DETAILED ACTION
Response to Arguments
Prior Art Reiection:
Applicant's arguments to independent claims 1 and 9 have been fully considered but they are deemed not persuasive.
In response to the argument, please see the new mapping in below.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1, 9, 11-14, 18-20 are rejected under 35 U.S.C. 102 (a)(1) as being anticipated by (US20070116286 A1) hereafter referred to as “Yuan”.
Regarding to claim 1:
Yuan discloses A quantum bit decoding apparatus comprising:
a demodulation apparatus, comprising ([0034] FIG. 1 is a schematic of a decoder. Fig. 3 [0101] Alice encodes her photons … and Bob decodes using four measurements):
an optical modulator, comprising:
an input beam splitter to receive a photon havinq a quantum bit encoded in a property of the photon (fig. 3, [0073] Bob's equipment 103 comprises WDM (wavelength division multiplexing) coupler 141 (that spits to 142 and 144). [0075] The signal pulses which are separated from the clock pulses by WDM coupler 141. [0074] Bob first de-multiplexes the transmitted signal received from Alice 101 via fibre 105 using the WDM coupler 141 [0058] The sender "Alice" 101 sends encoded photons to receiver "Bob" over optical fibre 105. [0101] Alice encodes her photons to one of four different phase delays: 0.degree., 90.degree., 180.degree. and 270.degree. and Bob decodes using four measurement bases: 0.degree., 90.degree., 180.degree. and 270.degree. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob. For each photon, Bob chooses at random in which basis to measure);
one of a phase modulator or polarization rotor to apply randomly one of a plurality of modulation values to the property of the photon to produce a randomly modulated photon ([0073] [0073] Bob's equipment 103 comprises WDM coupler 141, a clock recovery unit 142 connected to an output of coupler 141, a polarisation controller 144 [0025] The decoder is primarily intended for use in performing a quantum measurement. For example, the decoder may comprise an interferometer and is configured to apply phase shifts as said first and second operators or the decoder may comprise a polarisation rotator and is configured to apply polarisation rotations as said first and second operators … the roles and "bit values" assigned to the two detectors may be reversed. [0004] For polarisation encoding, one basis may be defined by vertically or horizontally polarising a photon and the other basis is defined by two polarisation states at 45.degree. to the vertical and horizontal states As the bit values may be reversed. Note: polarisation controller 144 is polarization rotor)
an optical router provided in a signal path after the optical modulator, to both receive and route the randomly modulated photon according to the quantum bit, to a first output and a second output (Fig. 3 where router 151 is located after 141 and 144. [0073] an entrance polarising beam splitter 151 connected to both: a long arm 153 containing a delay loop 154 and a variable delay line 157; and a short arm 152 containing a phase modulator 155. [0076] An entrance polarising beam splitter 151 divides the incident pulses with orthogonal linear polarisations. [0075] The signal pulses which are separated from the clock pulses by WDM coupler 141 are fed into a polarisation controller 144 to restore the original polarisation of the signal pulses. This is done so that signal pulses which travelled the short arm 131 in Alice's interferometer 133, will pass the long arm 153 in Bob's interferometer 156. Similarly, signal pulses which travelled through the long arm 132 of Alice's interferometer 133 will travel through the short arm 152 of Bob's interferometer)
an optical delay apparatus operatively connected to the demodulation apparatus, the optical delay apparatus comprising:
an optical combiner (see fig. 3 where two paths 152 and 153 combine to an optical combiner 158 of Bob);
a first optical path from the first output of the optical router to a first input of the optical combiner (see fig. 3 path 152. [0073] a long arm 153 containing a delay loop 154 and a variable delay line 157; and a short arm 152 containing a phase modulator 155 (this will output to a combiner 158 – see fig.3) The long arm 153 and short arm 152 are connected to an exit polarisation maintaining 50/50 fibre coupler 158); and
a second optical path from the second output of the optical router to a second input of the optical combiner (see fig. 3 path 153. [0073] a long arm 153 containing a delay loop 154 and a variable delay line 157 (this will output to a combiner 158 – see fig.3); and a short arm 152 containing a phase modulator 155 (this will output to a combiner 158 – see fig.3) The long arm 153 and short arm 152 are connected to an exit polarisation maintaining 50/50 fibre coupler 158)), the second optical path having a different optical path length to the first optical path to introduce a time delay between the first optical path and the second optical path ([0076] The long arm 153 of Bob's interferometer 156 contains an optical fibre delay loop 154 and a variable fibre delay line 157, and the short arm 152 contains a phase modulator 155 which is configured to apply a phase shift of .theta.), the optical combiner in communication with both the first optical path and the second optical path to receive the randomly modulated photon from any one of the first optical path and the second optical path (See Fig. 8 where two paths 152 and 153 combine to an optical combiner 158 of Bob. [0073] a long arm 153 containing a delay loop 154 and a variable delay line 157 (this will output to a combiner 158 – see fig.3); and a short arm 152 containing a phase modulator 155 (this will output to a combiner 158 – see fig.3) The long arm 153 and short arm 152 are connected to an exit polarisation maintaining 50/50 fibre coupler 158. [0076] This ensures that signal pulses taking either arm will have the same polarisation at the exit 50/50 polarisation maintaining coupler 158 )
a detection apparatus connected to the optical delay apparatus, the detection apparatus comprising (see fig. 3, detector 161 and 163 connecting to158) :
one optical receiver to detect the randomly modulated photon received from the optical combiner via optical paths with a different time delay, the one optical receiver being a single photon photodetector (see Fig. 8 plurality of optical paths 152, 153; optical combiner 158 and SPD 161. [0073] a long arm 153 containing a delay loop 154 and a variable delay line 157 and a short arm 152 containing a phase modulator 155 [0076] The two arms 152, 153 are connected to a 50/50 polarisation maintaining fibre coupler 158 with a single photon detector A 161. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob [0081] By controlling the voltages applied to their phase modulators 134, 155, Alice and Bob determine in tandem whether paths (i) and (ii) undergo constructive or destructive interference at detectors A 161. [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161); and
processing circuitry to determine a time delay of the detected randomly modulated photon relative to a reference time (Fig. 13 [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob. [0139] A pulse travelling through the long arm 411 (referred to below as the `late pulse`) will lag that travelling through the short arm 415 (`early pulse`) by a time delay. Fig. 9 [0073] two single photon detectors A 161, B 163 connected to the output arms of interferometer 156 … to process detection results … whether or not to inverse the detection results for each photon detection event. Fig. 14 [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0196] Such feedback times are sufficient since the phase drift of the Alice and Bob's interferometers occurs over much longer time scales. For highly unstable environment, much shorter feedback times, for example, 0.1 ms, may be employed. Alternatively, the feedback signal may be used to recalibrate the zero point of both phase modulators. Fig. 9 [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161 (and thus destructive interference at detector B 163) for zero phase difference between Alice and Bob's phase modulators. Thus for zero phase difference between Alice's and Bob's modulators and for a perfect interferometer with 100% visibility, there will be a negligible count rate at detector B 163 and a finite count rate at A 161. Note: shorter time (0.1ms) is a reference time), and
determine a value of the quantum bit based at least in part on the determined time delay ([0139] A pulse travelling through the long arm 411 (referred to below as the `late pulse`) will lag that travelling through the short arm 415 (`early pulse`) by a time delay. [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0196] The reference detector R 465 … Such feedback times are sufficient since the phase drift of the Alice and Bob's interferometers occurs over much longer time scales. For highly unstable environment, much shorter feedback times, for example, 0.1 ms, may be employed. Alternatively, the feedback signal may be used to recalibrate the zero point of both phase modulators. [0023] Bob (comprises detectors) can modulate his phase modulator to four different phase delays: 0.degree., 90.degree., 180.degree., and 270.degree. Phase delay difference 180.degree. directs a photon to an opposite detector than that for a phase delay of 0.degree. In BB84 protocol, Bob uses 0.degree. and 90.degree. phase delays to decode photons sent by Alice. Decoding using BB84 is asymmetrical, because photons of each encoding state do not have equal probability of arriving at Bob's two detectors. With extra phase delay of 180.degree., Bob can switch a photon to an opposite detector. Bob randomly selects whether or not to apply such detection inversion means, so that photons arrive at two detectors with equal probabilities. Therefore, decoding with detection inversion means is inherently symmetrical).
Regarding to claim 9:
Yuan discloses A method of quantum bit (qubit) decoding ([0032] a decoder configured to perform a measurement on said input signal), the method comprising steps of:
receiving via an optical path of a plurality of optical paths a randomly modulated photon having a qubit encoded in a property of the photon (See fig.3 for plurality of optical paths [0027] said sending unit comprising an encoder configured to encode carriers setting quantum states of the carriers. [0005] The phase state for each photon transmitted from sender (often referred to as Alice) to receiver (referred to as Bob) is chosen to be in one of the four states … These four states correspond to 0 and 1 in the two non-orthogonal encoding bases. Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob), each optical path of the plurality of optical paths configured to transport a randomly modulated photon with a different delay determined by the random modulation of the photon ([0160] The signal/reference pulse separator 224 comprises an entrance fibre optic coupler 220 with a first output connected to a long arm 222 with a loop of fibre 223 designed to cause an optical delay and short arm 221 (note: 221 and 222 are a plurality of optical paths). [0084] Alice using her phase modulator 134 (on short arm) to apply one of 4 different phase shifts .theta., namely 0.degree., 90.degree., 180.degree. or 270.degree. [0022] Alice encodes each pulse with one of four phase delays (on short arm): 0.degree., 90.degree., 180.degree., and 270.degree. by setting her phase modulator to one of four. [0064] a fibre optic phase modulator 134 (on short arm) which is configured to apply a phase shift of .theta. (where .theta.=0.degree., 90.degree., 180.degree. or 270.degree. … The length difference of the two arms 131 and 132 corresponds to an optical propagation delay of t.sub.delay), the photon being modulated by randomly applying a modulation values to the property of the photon to produce the qubits ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob. [0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states. Note: quantum states is qubits);
detecting, via a same single single photon detector (SPD) the randomly modulated photon received via any optical path of the plurality of optical paths (see mapping on claim 1));
determining a first time delay of the detected randomly modulated photon relative to a reference time (see mapping on claim 1);and
determining a value of the qubit according to the determined first time delay (see mapping on claim 1)
[Rejection rational for claim 1 is applicable].
Regarding to claim 11:
Yuan discloses The method as claimed in claim 9, comprising:
receiving the randomly modulated photon has a plurality of qubits respectively encoded in a plurality of properties of the photon and wherein the method comprises steps of (See fig.3 for plurality of optical paths [0027] said sending unit comprising an encoder configured to encode carriers setting quantum states of the carriers. [0005] The phase state for each photon transmitted from sender (often referred to as Alice) to receiver (referred to as Bob) is chosen to be in one of the four states … These four states correspond to 0 and 1 in the two non-orthogonal encoding bases. Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob [0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … the assignment of bit values to particular qubit states):
randomly applying one of a plurality of first modulation values to a first one of the plurality of properties of the photon ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … the assignment of bit values to particular qubit states. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob. Note: photon polarisation or phase delay are properties of the photon), the first modulation value to decode a first one of the plurality of quantum bits ([0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states; [0032] measuring said carriers using a decoder configured to perform a measurement on said input signal using two operators. Note: quantum states are modulation values; quantum bit state 0 or 1 is qubit);
randomly applying one of a plurality of second modulation values to a second one of the plurality of properties of the photon ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … the assignment of bit values to particular qubit states. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob. Note: photon polarisation or phase delay are properties of the photon), the second modulation value to decode a second one of the plurality of quantum bits ([0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states; [0032] measuring said carriers using a decoder configured to perform a measurement on said input signal using two operators. Note: quantum states are modulation values; quantum bit state 0 or 1 is qubit);
applying a time delay to the randomly modulated photon, the applied time delay depending on at least one of the decode first quantum bit and the decoded second quantum bit (fig. 1, [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob. [0023] Bob (comprises detectors) can modulate his phase modulator to four different phase delays: 0.degree., 90.degree., 180.degree., and 270.degree. Phase delay difference 180.degree. directs a photon to an opposite detector than that for a phase delay of 0.degree. In BB84 protocol, Bob uses 0.degree. and 90.degree. phase delays to decode photons sent by Alice. [0049] a loop of fibre 511 designed to cause an optical delay. [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161 (and thus destructive interference at detector B 163) for zero phase difference between Alice and Bob's phase modulators. Thus for zero phase difference between Alice's and Bob's modulators and for a perfect interferometer with 100% visibility, there will be a negligible count rate at detector B 163 and a finite count rate at A 161);
detecting by the one SPD, the randomly modulated photon received via any optical path of the plurality of optical paths (See Fig. 8 where two paths 152 and 153 combine to an optical combiner 158 then routing to 161. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob [0073] two single photon detectors A 161, B 163 connected to the output arms of interferometer 156 … to process detection results … Detection processor 177 is connected to inversion controller 175 and receives instructions on whether or not to inverse the detection results for each photon detection event. [0107] it is possible to design the system so that it only has one detector 161A. Such a system is shown in FIG. 8)); and
determining a second time delay by which the detected randomly modulated photon is delayed relative to a reference time (Fig. 13 [0139] A pulse travelling through the long arm 411 (referred to below as the `late pulse`) will lag that travelling through the short arm 415 (`early pulse`) by a time delay. [0023] Bob (comprises detectors) can modulate his phase modulator to four different phase delays: 0.degree., 90.degree., 180.degree., and 270.degree. …, so that photons arrive at two detectors with equal probabilities. Therefore, decoding with detection inversion means is inherently symmetrical. Fig. 14 [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0196] Such feedback times are sufficient since the phase drift of the Alice and Bob's interferometers occurs over much longer time scales. For highly unstable environment, much shorter feedback times, for example, 0.1 ms, may be employed. Alternatively, the feedback signal may be used to recalibrate the zero point of both phase modulators. Fig. 9 [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161 (and thus destructive interference at detector B 163) for zero phase difference between Alice and Bob's phase modulators. Thus for zero phase difference between Alice's and Bob's modulators and for a perfect interferometer with 100% visibility, there will be a negligible count rate at detector B 163 and a finite count rate at A 161. Note: shorter time (0.1ms) is a reference time); and
determining the quantum bit according to the determined second time delay ([0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161 (and thus destructive interference at detector B 163) for zero phase difference between Alice and Bob's phase modulators. Thus for zero phase difference between Alice's and Bob's modulators and for a perfect interferometer with 100% visibility, there will be a negligible count rate at detector B 163 and a finite count rate at A 161), wherein the first property of the photon and the second property of the photon are different, non- commutable properties of a photon quantum state of the photon ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states. [0025] a polarisation rotator 108 configured to rotate the polarisation of pulses from signal laser diode 107. [0017] pulses containing more than one photon. See spec [0018] non-commutable properties of the photon quantum state comprise polarization, phase and spin).
Regarding to claim 12:
Yuan discloses The method as claimed in claim 11, further comprising:
randomly applying one of a plurality of third modulation values to a third one of the plurality of properties of the photon ([0084] Alice will use her emitter to send photons having one of four phase states. [0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states), the third modulation value to decode a third one of the plurality of quantum bits (([0084] Alice will use her emitter to send photons having one of four phase states [0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states; [0032] measuring said carriers using a decoder configured to perform a measurement on said input signal using two operators), the third property being a third, different non-commutable property of the photon quantum state ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states. [0025] a polarisation rotator 108 configured to rotate the polarisation of pulses from signal laser diode 107. [0017] pulses containing more than one photon. See spec [0018] non-commutable properties of the photon quantum state comprise polarization, phase and spin), wherein the second time delay depends on at least one of the first quantum bit, the second quantum bit and the third quantum bit ([0084] Alice will use her emitter to send photons having one of four phase states. [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector).
Regarding to claim 13:
Yuan discloses The method as claimed in claim 11, wherein the time delay depends on each of the first quantum bit, second quantum bit, and third quantum bit ([0084] Alice will use her emitter to send photons having one of four phase states. [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector).
Regarding to claim 14:
Yuan discloses The method as claimed in claim 11, wherein the non-commutable properties of the photon quantum state comprise polarization, phase and spin ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states. [0025] a polarisation rotator 108 configured to rotate the polarisation of pulses from signal laser diode 107. [0017] pulses containing more than one photon .see spec [0018] non-commutable properties of the photon quantum state comprise polarization, phase and spin).
Regarding to claim 18:
Yuan discloses The method as claimed in claim 9, comprising:
receiving the randomly modulated photon has a plurality of qubits respectively encoded in a plurality of properties of the photon and wherein the method comprises steps of (See fig.3 for plurality of optical paths [0027] said sending unit comprising an encoder configured to encode carriers setting quantum states of the carriers. [0005] The phase state for each photon transmitted from sender (often referred to as Alice) to receiver (referred to as Bob) is chosen to be in one of the four states … These four states correspond to 0 and 1 in the two non-orthogonal encoding bases. Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob [0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … the assignment of bit values to particular qubit states)
randomly applying one of a plurality of first modulation values to a first one of the plurality of properties of the photon ([0027] said sending unit comprising an encoder configured to encode carriers setting quantum states of the carriers. [0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … the assignment of bit values to particular qubit states. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob), the first modulation values to decode a first one of the plurality of quantum bits ([0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states; [0032] measuring said carriers using a decoder configured to perform a measurement on said input signal using two operators. Note: quantum states are modulation values; quantum bit state 0 or 1 is quantum bit);
randomly applying one of a plurality of second modulation values to a second one of the plurality of properties of the photon ([0027] said sending unit comprising an encoder configured to encode carriers setting quantum states of the carriers. [0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … the assignment of bit values to particular qubit states. [0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob), the second modulation values configured for decoding a second one of the plurality of qubits ([0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states; [0032] measuring said carriers using a decoder configured to perform a measurement on said input signal using two operators. Note: quantum states are modulation values; quantum bit state 0 or 1 is qubit);
applying a time delay to the randomly modulated photon, the applied time delay depending on at least one of the first quantum bit and the second quantum bit ((see mapping on claim 11);
detecting the randomly modulated photon ([0005] Alice chooses at random the bit value (0 or 1) and the encoding basis for each photon and transmits the appropriate state to Bob [0073] two single photon detectors A 161, B 163 … to process detection results … whether or not to inverse the detection results for each photon detection event); and
determining a second time delay by which the detected randomly modulated photon is delayed relative to the reference time (Fig. 13 [0139] A pulse travelling through the long arm 411 (referred to below as the `late pulse`) will lag that travelling through the short arm 415 (`early pulse`) by a time delay. [0023] Bob (comprises detectors) can modulate his phase modulator to four different phase delays: 0.degree., 90.degree., 180.degree., and 270.degree. …, so that photons arrive at two detectors with equal probabilities. Therefore, decoding with detection inversion means is inherently symmetrical. Fig. 14 [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0196] Such feedback times are sufficient since the phase drift of the Alice and Bob's interferometers occurs over much longer time scales. For highly unstable environment, much shorter feedback times, for example, 0.1 ms, may be employed. Alternatively, the feedback signal may be used to recalibrate the zero point of both phase modulators. Fig. 9 [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161 (and thus destructive interference at detector B 163) for zero phase difference between Alice and Bob's phase modulators. Thus for zero phase difference between Alice's and Bob's modulators and for a perfect interferometer with 100% visibility, there will be a negligible count rate at detector B 163 and a finite count rate at A 161. Note: shorter time (0.1ms) is a reference time); and
determining the quantum bit according to the determined second time delay([0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector, and compensate any phase drifts of Alice or Bob's interferometers. [0196] The reference detector R 465 … Such feedback times are sufficient since the phase drift of the Alice and Bob's interferometers occurs over much longer time scales. For highly unstable environment, much shorter feedback times, for example, 0.1 ms, may be employed. Alternatively, the feedback signal may be used to recalibrate the zero point of both phase modulators. [0082] The variable delay line 157 can be set such that there is constructive interference at detector A 161 (and thus destructive interference at detector B 163) for zero phase difference between Alice and Bob's phase modulators. Thus for zero phase difference between Alice's and Bob's modulators and for a perfect interferometer with 100% visibility, there will be a negligible count rate at detector B 163 and a finite count rate at A 161, wherein the first property of the photon and the second property of the photon are different, non- commutable properties of a photon quantum state of the photon ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states. [0025] a polarisation rotator 108 configured to rotate the polarisation of pulses from signal laser diode 107. [0017] pulses containing more than one photon. See spec [0018] non-commutable properties of the photon quantum state comprise polarization, phase and spin).
Regarding to claim 19:
Yuan discloses The method as claimed in claim 18, further comprising a step of randomly applying one of a plurality of third modulation values to a third one of the plurality of properties of the photon ([0084] Alice will use her emitter to send photons having one of four phase states. [0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states), the third modulation values configured for decoding a third one of the plurality of qubits ([0084] Alice will use her emitter to send photons having one of four phase states [0031] sending an input signal having quantum information encoded on said input signal in the form of one of at least four quantum states; [0032] measuring said carriers using a decoder configured to perform a measurement on said input signal using two operators), the third property being a third, different non- commutable property of the photon quantum state ([0004] In BB84, the bit state 0 or 1 is encoded onto a certain physical property of a photon, such as polarisation or phase delay … phase shift of 0.degree. or 180.degree. to a photon … shift of 90.degree. or 270.degree. to a photon … the assignment of bit values to particular qubit states. [0025] a polarisation rotator 108 configured to rotate the polarisation of pulses from signal laser diode 107. [0017] pulses containing more than one photon. See spec [0018] non-commutable properties of the photon quantum state comprise polarization, phase and spin), wherein the second time delay depends on at least one of the first quantum bit, the second quantum bit and the third quantum bit ([0084] Alice will use her emitter to send photons having one of four phase states. [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector).
Regarding to claim 20:
Yuan discloses The method as claimed in claim 19, wherein the second time delay depends on each of the first quantum bit, second quantum bit, and third quantum bit ([0084] Alice will use her emitter to send photons having one of four phase states. [0194] Bob uses any variation in the count rate measured by the reference detector R 465 as a feedback signal to the variable delay line 257. Thus the optical delay is adjusted to stabilise the counting rate in the reference detector).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action.
This action is a final rejection and is intended to close the prosecution of this application. Applicant’s reply under 37 CFR 1.113 to this action is limited either to an appeal to the Patent Trial and Appeal Board or to an amendment complying with the requirements set forth below.
If applicant should desire to appeal any rejection made by the examiner, a Notice of Appeal must be filed within the period for reply identifying the rejected claim or claims appealed. The Notice of Appeal must be accompanied by the required appeal fee.
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A reply under 37 CFR 1.113 to a final rejection must include the appeal from, or cancellation of, each rejected claim. The filing of an amendment after final rejection, whether or not it is entered, does not stop the running of the statutory period for reply to the final rejection unless the examiner holds the claims to be in condition for allowance. Accordingly, if a Notice of Appeal has not been filed properly within the period for reply, or any extension of this period obtained under either 37 CFR 1.136(a) or (b), the application will become abandoned.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to HIEN DOAN whose telephone number is 571 272-4317. The examiner can normally be reached on Monday-Thursday and biweekly Friday 9am-6pm.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, SRIVASTAVA VIVEK can be reached on 571-272-7304(571)272-7304. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative or access to the automated information system, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/HIEN V DOAN/Examiner, Art Unit 2449
/VIVEK SRIVASTAVA/Supervisory Patent Examiner, Art Unit 2449
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