Measurement based photonic quantum computing system

1 . A measurement based photonic quantum computing system comprising:

an optical input generator comprising:

a paired input source configured to receive optical paired inputs, and

a first time delay unit,

wherein the optical input generator is configured for:

receiving first optical paired inputs, and second optical paired inputs, wherein the first optical paired inputs are first optical entangled paired inputs and the second optical paired inputs are second optical entangled paired inputs, or

receiving first optical paired inputs and second optical paired inputs, and generating first optical entangled paired inputs and second optical entangled paired inputs from the first optical paired inputs, and second optical paired inputs, respectively; and

inducing a first predefined relative time delay using the first time delay unit into each optical entangled paired inputs for making one mode of the first and one mode of the second entangled optical paired inputs into coexisting optical inputs, representing a logic level of the quantum computing system; and

a delocalized measurement architecture comprising:

a second time delay unit,

a third time delay unit,

two optical detectors,

a beam splitter,

a first and second variable path-couplers,

wherein the delocalized measurement architecture is configured for gate implementation of the quantum computing system by:

optically interfering coexisting optical inputs for generating intermediate outputs;

optically interfering by the first and the second variable path-couplers for each intermediate outputs a first mode of the intermediate outputs to a second mode of first or second neighboring intermediate outputs, respectively, for generating interfered outputs; and

detecting by the two optical detectors each mode of the intermediate outputs and the interfered outputs.

2 . The measurement based photonic quantum computing system according to claim 1 , wherein the two optical detectors are two homodyne optical detectors.

3 . The measurement based photonic quantum computing system according to claim 1 , wherein the delocalized measurement architecture is further configured for inducing a second predefined relative time delay into each intermediate outputs.

4 . The measurement based photonic quantum computing system according to claim 3 , wherein the delocalized measurement architecture is further configured for inducing a third predefined relative time delay into each interfered outputs.

5 . The measurement based photonic quantum computing system according to claim 4 , wherein:

the first predefined relative time delay is n times m time units, wherein n is a positive integer and >0, m is a positive integer; and

wherein the second predefined relative time delay is 1 time unit and the third predefined relative time delay is n−1 time units.

6 . The measurement based photonic quantum computing system according to claim 5 , wherein the first and the second optical paired inputs are received n times m time units apart.

7 . The measurement based photonic quantum computing system according to claim 1 , wherein the delocalized measurement architecture is configured for time-delaying the first mode of the intermediate outputs by:

the second predefined relative time delay; or

the second and the third predefined relative time delays;

relative to the second mode of the first or the second neighboring intermediate outputs, respectively, for causing the first mode of the intermediate outputs to be coexisting with the second mode of the first or the second neighboring intermediate outputs at the first or the second variable path-coupler, respectively.

8 . The measurement based photonic quantum computing system according to claim 1 , wherein the measurement based photonic quantum computing system comprises n times m sets of the optical input generator and the delocalized measurement architecture, wherein n is a positive integer and >0, m is a positive integer.

9 . The measurement based photonic quantum computing system according to claim 8 , wherein the second mode of the first or the second neighboring intermediate outputs is an intermediate output of a first or a second set of the optical input generator and the delocalized measurement architecture different from the set of the optical input generator and the delocalized measurement architecture of the first mode of the intermediate outputs.

10 . The measurement based photonic quantum computing system according to claim 9 , wherein the first predefined relative time delay is one time unit, and the first and the second optical paired inputs are received one time unit apart.

11 . The measurement based photonic quantum computing system according to claim 1 , wherein the optical input generator comprises a two-mode squeezing generator configured for generating the optical paired inputs.

12 . The measurement based photonic quantum computing system according to claim 11 , wherein the two-mode squeezing generator is:

a first two-mode gate;

a first balanced path-coupler;

a controlled-Z gate;

a parametric down-convertor; or

a four-wave mixer.

13 . The measurement based photonic quantum computing system according to claim 1 , wherein the optical input generator comprises a two-mode squeezing generator configured for generating an entangled two-mode squeezed state.

14 . The measurement based photonic quantum computing system according to claim 1 , wherein the optical input generator comprises a two-mode entangled Gottesman-Kitaev-Preskill (GKP) qubits generator, configured for interfering or coupling optical inputs for generating the received optical paired inputs.

15 . The measurement based photonic quantum computing system according to claim 14 , wherein the two-mode entangled GKP qubits generator is:

a first two-mode gate, a first balanced path-coupler or a controlled gate, for coupling two GKP states; or

configured for direct generation of two entangled GKP states.

16 . The measurement based photonic quantum computing system according to claim 1 , wherein the optical input generator comprises a two-mode entangled Gottesman-Kitaev-Preskill (GKP) qubits generator, configured for interfering or coupling optical inputs for generating the received optical paired inputs, as two entangled GKP qubits.

17 . The measurement based photonic quantum computing system according to claim 1 , wherein the optical input generator comprises two first switches configured for switching continuously between:

a first position configured for transferring squeezed vacuum states, |0≥ Sq , as optical inputs; and

a second position configured for transferring Gottesman-Kitaev-Preskill (GKP) states of encoded 1-level systems, Ø≥ GKP , as optical inputs;

to the first balanced path-coupler, or the optical input generator comprises two second switches configured for switching continuously between;

a first position configured for transferring an entangled two-mode squeezed vacuum states as optical paired inputs; and

a second position configured for transferring an entangled GKP state as optical paired inputs.

18 . The measurement based photonic quantum computing system according to claim 1 , wherein the optical input generator comprises:

a first time-delay unit configured for performing the first predefined relative time delay, wherein the first time-delay unit comprises an input and an output; and

a second switch positioned at the input or the output of the first time-delay unit, wherein the second switch in a closed position is configured for transferring a state of encoded information to the input or the output of the first time-delay unit.

19 . The measurement based photonic quantum computing system according to claim 18 , wherein the state of encoded information is a Gottesman-Kitaev-Preskill (GKP)-qubit state, |ψ> GKP .

20 . A second measurement based photonic quantum computing system comprising a number, from one to N, of the measurement based photonic quantum computing systems according to claim 1 , wherein each of the number of measurement based photonic quantum computing systems is configured for transferring:

one mode of the first optical paired inputs of each of the N measurement based photonic quantum computing systems to be coexisting with another mode of the first optical paired inputs of the next measurement based photonic quantum computing system; or

one mode of the coexisting optical inputs of each measurement based photonic quantum computing system to be coexisting with another mode of coexisting optical inputs of the next measurement based photonic quantum computing system;

wherein the next measurement based photonic quantum computing system for the Nth measurement based photonic quantum computing system is the first measurement based photonic quantum computing system.

21 . A temporal delocalized measurement device, comprising:

a balanced path-coupler configured for interfering received coexisting optical inputs and for interfering received first or second neighboring coexisting optical inputs for generating intermediate outputs, and for generating first or second neighboring intermediate outputs, respectively;

a second time delay unit;

a third time delay unit;

first and second variable path-couplers positioned after the second time delay unit and the third time delay unit, respectively; and

two optical detectors;

wherein the second time delay unit and the third time delay unit are configured for inducing a second predefined relative time delay and a further third predefined relative time delay, respectively, into each of the intermediate outputs and into the first or second neighboring intermediate outputs for causing a first mode of the intermediate outputs to be coexisting with a second mode of the second or the third neighboring intermediate outputs at the first or at the second variable path-coupler, respectively;

wherein the first and the second variable path-couplers are configured for optically interfering the first mode of the intermediate outputs and the second mode of the second or the third neighboring intermediate outputs, respectively, for generating interfered outputs; and

wherein the two optical detectors are configured for detecting each mode of the intermediate outputs and the interfered outputs.

22 . The temporal delocalized measurement device according to claim 21 , wherein the two optical detectors are two homodyne optical detectors.

23 . A n times m spatial delocalized measurement device, wherein n is a positive integer and >0, m is a positive integer, the device comprising:

a balanced path-coupler configured for interfering received first and second coexisting optical inputs and for generating first and second intermediate outputs;

first and second variable path-couplers for the first intermediate output;

first and second variable path-couplers for the second intermediate output; and

first and second optical detectors;

wherein the first and the second variable path-couplers for the first intermediate output of an i th ,j th spatial delocalized measurement device of the spatial delocalized measurement devices are configured for interfering the first intermediate output and a second intermediate output of an i+1 th ,j th spatial delocalized measurement device or for interfering the first interfered coexisting optical input and a second intermediate output of an i th ,j+1 th spatial delocalized measurement device, respectively, for generating a first interfered output;

wherein the first and the second variable path-couplers for the second intermediate output of the ith,jth spatial delocalized measurement device are configured for interfering the second intermediate output and a first intermediate output of an i−1 th ,j th spatial delocalized measurement device or for interfering the second intermediate output and a first intermediate output of an i th ,j−1 th spatial delocalized measurement device, respectively, for generating a second interfered output; and

wherein the first and second optical detectors are configured for simultaneously detecting the first intermediate output or the first interfered output, and the second intermediate output or the second interfered output, respectively.