Chip-scale transmitter for quantum cryptography

1 . A quantum cryptographic key distribution (QKD) transmitter, comprising;

an integrated photonic circuit configured to distribute encryption key material using quantum cryptographic mechanisms.

2 . The QKD transmitter of claim 1 , wherein the integrated photonic circuit is implemented on a single chip.

3 . The QKD transmitter of claim 1 , further comprising:

control electronics coupled to the integrated photonic circuit and configured to control the operation of the integrated photonic circuit.

4 . The QKD transmitter of claim 3 , wherein the integrated photonic circuit and control electronics are implemented on a single chip.

5 . The QKD transmitter of claim 3 , wherein the integrated photonic circuit and the control electronics are implemented on different chips.

6 . The QKD transmitter of claim 1 , wherein the integrated photonic circuit comprises:

a first photon source;

an interferometer coupled to the first photon source; and

a phase modulator coupled to the interferometer and configured to modulate a phase of photons emitted by the first photon source.

7 . The QKD transmitter of claim 6 , wherein the first photon source comprises a pulsed light source.

8 . The QKD transmitter of claim 6 , wherein the first photon source comprises a continuous wave light source and further comprising:

a semiconductor optical amplifier (SOA) coupled to an output of the first photon source

9 . The QKD transmitter of claim 6 , wherein the integrated photonic circuit further comprises:

an attenuator coupled to an output of the interferometer.

10 . The QKD transmitter of claim 9 , wherein the integrated photonic circuit further comprises:

a second photon source; and

a combiner coupled to an output of the second photon source and to an output of the attenuator.

11 . The QKD transmitter of claim 6 , wherein the interferometer comprises a Mach-Zehnder interferometer.

12 . The QKD transmitter of claim 1 , wherein the integrated photonic circuit is implemented in III-V semiconducting materials.

13 . The QKD transmitter of claim 1 , wherein the integrated photonic circuit is implemented in silica or silicon material.

14 . A system, comprising:

an interferometer formed in an integrated circuit;

a first laser formed in the integrated circuit and coupled to a first side of the interferometer;

an attenuator formed in the integrated circuit and coupled to a second side of the interferometer; and

a phase modulator formed in the integrated circuit and coupled to the interferometer.

15 . The system of claim 14 , wherein the interferometer, first laser, attenuator and phase modulator are integrated on a single chip.

16 . The system of claim 14 , further comprising:

a second laser formed in the integrated circuit; and

a combiner formed in the integrated circuit and coupled to the second laser and to an output of the attenuator.

17 . The system of claim 16 , further comprising:

an optical isolator coupled to an output of the combiner.

18 . A quantum cryptographic key distribution (QKD) transmitter, comprising;

an integrated photonic circuit configured to distribute encryption key material using quantum cryptographic mechanisms via multiple channels.

19 . The QKD transmitter of claim 18 , wherein the integrated photonic circuit is configured to wavelength division multiplex the multiple channels.

20 . The QKD transmitter of claim 18 , wherein the integrated photonic circuit is configured to time division multiplex the multiple channels.

21 . The QKD transmitter of claim 18 , the integrated photonic circuit further comprising:

a first portion of the integrated photonic circuit configured to distribute encryption key material using quantum cryptographic mechanisms via a first channel of the multiple channels; and

a second portion of the integrated photonic circuit configured to distribute encryption key material using quantum cryptographic mechanisms via a second channel of the multiple channels.

22 . The QKD transmitter of claim 21 , wherein the first portion of the integrated photonic circuit comprises:

a first interferometer;

a first laser coupled to an input of the first interferometer and configured to transmit light over the first channel of the multiple channels;

a first phase modulator coupled to the first interferometer; and

a first attenuator coupled to an output of the first interferometer.

23 . The QKD transmitter of claim 22 , wherein the second portion of the integrated photonic circuit comprises:

a second interferometer;

a second laser coupled to an input of the second interferometer and configured to transmit light over the second channel of the multiple channels;

a second phase modulator coupled to the second interferometer; and

a second attenuator coupled to an output of the second interferometer.

24 . The QKD transmitter of claim 23 , wherein the integrated photonic circuit further comprises:

a combiner coupled to an output of the first and second attenuators; and

an optical isolator coupled to an output of the combiner.

25 . A quantum cryptographic key distribution (QKD) transmitter, comprising;

an integrated photonic circuit configured to distribute encryption key material using at least one of dim light pulses or single photon light pulses and synchronization light pulses.

26 . The QKD transmitter of claim 25 , wherein the integrated photonic circuit uses 1 synchronization light pulse for N>=1 dim or single photon light pulses.

27 . The QKD transmitter of claim 25 , wherein the at least one of dim light or single photon light pulses comprise light pulses at a first wavelength.

28 . The QKD transmitter of claim 27 , wherein the synchronization light pulses comprise light pulses at a second wavelength, wherein the first wavelength is different than the second wavelength.