Abstract: Apparatus, systems and methods for pre-processing, analyzing, and storing genomic data through a scalable, distributed analysis system across a network is presented.

Abstract: A method and associated systems for using direct sums and invariance groups to optimize the testing of partially symmetric quantum-logic circuits is disclosed. A test system receives information that describes the architecture of a quantum-logic circuit to be tested. The system uses this information to organize the circuit's inputs into two or more mutually exclusive subsets of inputs. The system computes a direct sum of a set of groups associated with the subsets in order to generate an invariance group that contains one or more invariant permutations of the circuit's inputs. These invariant permutations can be used to reduce the number of tests required to fully verify the circuit for all possible input vectors. Once one specific input vector has been verified, there is no need to test other vectors that can be generated by performing any one of the invariant permutations upon the previously verified vector.

Abstract: Structures for scattering light at multiple wavelengths are disclosed. Scattering elements are fabricated with different geometric dimensions and arrangements, to scatter or focus light at the the same focal distance for each wavelength, or at different focal distances according to the desired application. The scattering elements fabricated on a substrate can be peeled off with a polymer matrix and attached to a lens to modify the optical properties of the lens.

Abstract: A laser system may include a laser source configured to generate a first laser light beam, a beamsplitter configured to split the first laser light beam into a plurality of second laser light beams, and a multi-channel acousto-optic modulator (AOM). The multi-channel AOM may include a common acousto-optic medium configured to receive the plurality of second laser light beams, and a respective phased array transducer comprising a plurality of electrodes coupled to the acousto-optic medium for each of the second laser light beams. The laser system may further include a plurality of radio frequency (RF) drivers configured to generate respective RF drive signals for the phased array transducer electrodes.

Abstract: An NP-processor is provided that is based on a computing environment consisting of a finite set of multiple-element triggers that are interconnected by common elements. The NP-processor has interference relations between the computing environment elements. Negative feedback is introduced and is intended for isolating an active state, which is the solution to the problem, from an exponential number of modes of oscillation in the computing environment.

Abstract: A photonic quantum memory is provided. The photonic quantum memory includes entanglement basis conversion module configured to receive a first polarization-entangled photon pair and to produce a second entangled photon pair. The second polarization-entangled photon pair can he a time-bin entangled or a propagation direction-entangled photon pair. The photonic quantum memory further includes a photonic storage configured to receive the second entangled photon pair from the basis conversion module and to store the second entangled photon pair.

Abstract: An optical transmitter includes: a set of reflective semiconductor optical amplifiers (RSOAs) or other reflective gain media, a set of ring filters, a set of intermediate waveguides, a shared waveguide, a shared loop mirror, and an output waveguide. Each intermediate waveguide channels light from an RSOA in proximity to an associated ring filter to cause optically coupled light to circulate in the associated ring filter. The shared waveguide is coupled to the shared loop mirror, and is located in proximity to the set of ring filters, so that light circulating in each ring filter causes optically coupled light to flow in the shared waveguide. Each RSOA forms a lasing cavity with the shared loop reflector, wherein each lasing cavity has a different wavelength associated with a resonance of its associated ring filter. The output waveguide is optically coupled to the shared loop mirror and includes an electro-optical modulator.

Abstract: Embodiments of the present invention provide a method and system of encryption, decryption, and encryption and decryption based on visible light communication. A transmit end performs a logical operation on an original data signal and a pseudocode signal varying with a unit interval to obtain a scrambling code signal, and sends the scrambling code signal in a form of a visible light signal. A receive end receives the visible light signal sent by the transmit end, and converts the visible light signal into a digital signal; and decodes the digital signal and a pseudocode signal varying with a unit interval, so as to obtain the original data signal. The visible light signal transmitted between the transmit end and the receive end is not original data, but a scrambling code signal varying with a unit interval, thereby improving security of the photonic Internet of Things.

Abstract: An optical feed network for a phased-array antenna may comprise a phase-based feed network that may include electro-optical phase shifting.

Abstract: An optical flip-flop circuit that includes an optical thyristor configured to receive a digital optical signal input and produce a digital signal output based on the ON/OFF state of the digital optical signal input. The optical flip-flop circuit further includes control circuitry operably coupled to the terminals of the optical thyristor. The control circuitry is configured to control switching operation of the optical thyristor in response to the level of a digital electrical signal input.

Abstract: A system, method, and apparatus for delayed optical logic gates based on slow light and enhanced nondegenerate four-wave mixing processes, where a single or multiple delayed optical routers are utilized for dark resonance interactions in which two-color lasers interact with a three-level nonlinear optical medium comprised of two ground states and one excited state through the nondegenerate four-wave mixing processes. The delayed optical logic mechanism is based on combination of single or multiple dark resonance-induced two-photon coherence conversion via slow light phenomenon. The two-photon coherence induced on the ground states is optically detected via nondegenerate four-wave mixing processes. The nondegenerate four-wave mixing generation is enhanced owing to dark resonance or electromagnetically induced transparency. The delayed optical logic gates have potential to keep up ultra-high-bandwidth optical information processing using relatively slow electronic processing devices.

Abstract: The current application is directed to methods and quantum circuits that prepare qubits in specified non-stabilizer quantum states that can, in turn, be used for a variety of different purposes, including in a quantum-circuit implementation of an arbitrary single-qubit unitary quantum gate that imparts a specified, arbitrary rotation to the state-vector representation of the state of an input qubit. In certain implementations, the methods and systems consume multiple magic-state qubits in order to carry out probabilistic rotation operators to prepare qubits with state vectors having specified rotation angles with respect to a rotation axis. These qubits are used as resources input to various quantum circuits, including the quantum-circuit implementation of an arbitrary single-qubit unitary quantum gate.

Abstract: Methods of operating an optical circuit switch and optical circuit switches are disclosed. A command to make an optical connection between a first port and a second port may be received. A determination whether or not input signal light is present at the first port may be made. When light is present at the first port, an optical connection may be made between the first port and the second port. When light is not present at the first port, the optical circuit switch may wait until light is present at the first port before making the connection.

Abstract: A system, method, and apparatus for delayed optical logic gates based on slow light and enhanced nondegenerate four-wave mixing processes, where a single or multiple delayed optical routers are utilized for dark resonance interactions in which two-color lasers interact with a three-level nonlinear optical medium comprised of two ground states and one excited state through the nondegenerate four-wave mixing processes. The delayed optical logic mechanism is based on combination of single or multiple dark resonance-induced two-photon coherence conversion via slow light phenomenon. The two-photon coherence induced on the ground states is optically detected via nondegenerate four-wave mixing processes. The nondegenerate four-wave mixing generation is enhanced owing to dark resonance or electromagnetically induced transparency. The delayed optical logic gates have potential to keep up ultra-high-bandwidth optical information processing using relatively slow electronic processing devices.

Abstract: A two-input bistable resonator that can be switched in a robust way by phase modulation of the input beams is presented. An optical flip-flop of the present invention may be embodied as a two-input Kerr resonator. The disclosed switching mechanism is compatible with cross-phase modulation induced by set and reset pulses for realization of an ultrafast, passive, all-optical memory element.

Abstract: The instant application describes display device for switching display mode between first display mode for displaying stereoscopic images with eyewear device which adjusts incident light amounts to the left and right eyes, and second display mode different from the first display mode. The display device includes signal generator which generates timing signals for notifying timings of increasing the incident light amount to the left and right eyes in the first and second display modes or stop signals for stopping the adjustment operation, as control signals for the adjustment operation; and transmitter which transmits the control signals to the eyewear device. During the first display mode, the transmitter transmits the timing signals for the first display mode. Switching operation from the first to second display mode causes the transmitter to transmit the stop signal and then the timing signal for the second display mode to the eyewear device.

Abstract: A system is disclosed that may include an Automatic Gain Control (AGC) module configured to automatically adjust the gain of a receiver, which is configured to receive a signal. The signal includes a number of commands, which have a characteristic command length and a characteristic command interval. The command length may have a substantially shorter duration than the command interval. The system may also include a slicer configured to interface to a command processor. The system includes a command processor communicatively coupled with the AGC module and/or the slicer for providing a notification to the AGC module and/or the slicer associated with the ends of the commands. The AGC module is configured to adjust the gain of the receiver and the slicer threshold voltage is updated when the notification is received from the command processor.

Abstract: We describe an integrated waveguide device that creates entanglement between a sequence of periodically spaced (in time) photons in a single input and output mode. The device consists of a polarization maintaining integrated waveguide chip containing a number of delay lines, integrated multimode interferometers with the potential for rapid switching, a polarization controller and off chip computer logic and timing. The device is capable of creating a diverse array of outputs such as linear cluster states and ring cluster states in a single output mode.

Abstract: An apparatus providing an integrated waveguide device that creates entanglement between a sequence of periodically spaced (in time) photons in a single input and output mode. The invention comprises a polarization maintaining integrated waveguide chip containing a number of delay lines, integrated multimode interferometers with the potential for rapid switching, a polarization controller and off chip computer logic and timing.

Abstract: An apparatus providing an integrated waveguide device that creates entanglement between a symmetrical sequence of periodically spaced (in time) photons in a single input and output mode. The invention comprises a polarization maintaining integrated waveguide chip containing a number of delay lines, integrated multimode interferometers with the potential for rapid switching, a polarization controller and off chip computer logic and timing.

Abstract: A method comprising providing an input signal to at least one input node of a computing reservoir by temporally encoding the input signal by modulating the at least one photonic wave as function of the input signal is described. The method further comprises propagating the at least one photonic wave via passive guided or unguided propagation between discrete nodes of the computing reservoir, in which each discrete node is adapted for passively relaying the at least one photonic wave over the passive interconnections connected thereto. The method also comprises obtaining a plurality of readout signals, in which each readout signal is determined by a non-linear relation to the at least one photonic wave in at least one readout node of the computing reservoir, and combining this plurality of readout signals into an output signal by taking into account a plurality of training parameters.

Abstract: A high density, low power, high performance information system, method and apparatus are described in which perpendicularly oriented processor and memory die stacks (130, 140, 150, 160, 170) include integrated deflectable MEMS optical beam waveguides (e.g., 190) at each die edge to provide optical communications (182-185) in and between die stacks by supplying deflection voltages to a plurality of deflection electrodes (195-197) positioned on and around each MEMS optical beam waveguide (193-194) to provide two-dimensional alignment and controlled feedback to adjust beam alignment and establish optical communication links between die stacks.

Abstract: Disclosed herein are atom phase-controlled double rephasing-based quantum memory and a double-rephased photon echo method therefor. The atom phase-controlled double rephasing-based quantum memory includes an optical medium and an optical pulse generation unit. The optical medium has three energy levels (|1>, |2> and |3>), receives one or more optical pulses from an optical pulse generation unit, and generates output light that satisfies phase matching conditions. The optical pulse generation unit generates at least five optical pulses that resonate among the energy levels of the optical medium.

Abstract: A method and device for optimal processing of a plurality of sets of coherent states of lights. The method includes: receiving a light having a coherent state; splitting the coherent state into a plurality of identical states (slices), each a coherent state with lower intensity than that of the received coherent state; transferring the information of each of the identical coherent states into a qubit; compressing the quantum information of the qubit into a quantum memory; and quantum processing the quantum information from the quantum memory.

Abstract: An optical device comprises an optical device stage, which comprises an optical input, an optical AND gate, an optical flip-flop and an optical output. The optical input is arranged to receive an optical input pulse at an input wavelength. The optical AND gate comprises a first input arranged to receive a part of said optical input pulse, a second input arranged to receive at least a part of a flip-flop optical output signal, and an output. The optical AND gate is arranged to generate an AND gate optical output pulse dependent on said flip-flop optical output signal. The optical flip-flop comprises a first input arranged to receive a further part of said optical input pulse, a second input arranged to receive a said AND gate optical output pulse, and an output. The optical flip-flop is arranged to generate said flip-flop output signal at a flip-flop output wavelength. At least a part of the flip-flop output signal is provided to said output.

Abstract: A birefringent reflectarray having a planar metasurface containing metallic patches of subwavelength dimension is provided. The reflectarray is capable of simultaneously reflecting, concentrating, and splitting incident infrared light into two orthogonal linearly polarized reflections, and transforms the phase front of an incoming polarized light to a desired phase for the two reflections. Also provided is an optical modulator having a metasurface containing layers of nanoantennas of subwavelength dimension, and capable of modulating the phase and amplitude of light scattered from the modulator. The optical modulator has ability to perform computation through processing of light.

Abstract: An electromagnetically induced transparent (EIT)-based photonic logic gate. The electromagnetically induced transparent (EIT)-based photonic logic gate is a photonic crystal (PC) and electromagnetically induced transparent (EIT)-based stacked layer which is constituted by a photonic crystal (PCs) layers and an electromagnetically induced transparent material layers. For the photonic crystal (PCs) and electromagnetically induced transparent (EIT)-based stacked layer, a probe field is an input signal which is emitted from the photonic crystal layer and a control field is a control signal which is emitted from the electromagnetically induced transparent material layers. The probe field is an input signal which is emitted from the electromagnetically induced transparent material layers. By varying the detune frequency of probe field and Rabi frequency of control field, the band gap structure can be adjusted.

Abstract: A random number generator includes a light source emitting light at a first frequency, an optical unit including an optical component configured to receive light at the first frequency and emit light at a second frequency, and a measurement unit configured to receive light at the second frequency, and generate a random output value related to a phase parameter of the light at the second frequency.

Abstract: A monolithic or hybrid integrated optical information processor or optical information processing system having a plurality of non-quadratic phase optical elements, at least one LED array, and plurality of light modulating array elements, each controlled by respective control signals, the system arranged so that each light modulating array element lies in a different plane. In some implementations, at least a portion of the resulting system is implemented in a stack of component materials. In an implementation, an LED array is used as an image source and another LED array is used as an image sensor to transform the processed image into an electrical output.

Abstract: Embodiments of the present invention provide systems and methods to robustly inter-convert between polarization-entangled photon pairs and time-entangled photon pairs, such that produced polarization-entangled photons pairs can be converted into time-entangled photon pairs, stored as time-entangled photon pairs to preserve the entanglement for longer periods of time, and then converted back to polarization-entangled photon pairs when ready for manipulation, processing, and measurement by a quantum application.

Abstract: Optical computing devices are disclosed. One optical computing device includes an electromagnetic radiation source that emits electromagnetic radiation into an optical train to optically interact with a sample and at least one integrated computational element, the sample being configured to generate optically interacted radiation. A sampling window is arranged adjacent the sample and configured to allow transmission of the electromagnetic radiation therethrough and has one or more surfaces that generate one or more stray signals. A first focal lens is arranged to receive the optically interacted radiation and the one or more stray signals and generate a primary focal point from the optically interacted radiation. A structural element defines a spatial aperture aligned with the primary focal point such that the optically interacted radiation is able to pass therethrough while transmission of the one or more stray signals is substantially blocked by the structural element.

Abstract: Optical computing devices are disclosed. One optical computing device includes an electromagnetic radiation source that emits electromagnetic radiation into an optical train to optically interact with a sample and at least one integrated computational element, the sample being configured to generate optically interacted radiation. A sampling window is arranged adjacent the sample and configured to allow transmission of the electromagnetic radiation therethrough and has one or more surfaces that generate one or more stray signals. A first focal lens is arranged to receive the optically interacted radiation and the one or more stray signals and generate a primary focal point from the optically interacted radiation. A structural element defines a spatial aperture aligned with the primary focal point such that the optically interacted radiation is able to pass therethrough while transmission of the one or more stray signals is substantially blocked by the structural element.

Abstract: Various embodiments of the present invention are directed to arbitration systems and methods. In one embodiment, an arbitration system comprises a loop-shaped arbitration waveguide (602), a loop-shaped hungry waveguide (603), and a loop-shaped broadcast waveguide (604). The arbitration, hungry, and broadcast waveguides optically coupled to a home node and a number of requesting nodes. The arbitration waveguide transmits tokens injected by the home node. A token extracted by a requesting node grants the node access to a resource for the duration or length of the token. The hungry waveguide transmits light injected by the home node. A requesting node in a hungry state extracts the light from the hungry waveguide. The broadcast waveguide transmits light injected by the home node such that the light indicates to requesting nodes not in the hungry state to stop extracting tokens from the arbitration waveguide.

Abstract: A component comprising a qubit and a controller for said qubit, said component comprising a quantum dot and an excitation portion configured to produce a neutral exciton state in said quantum dot to form said qubit, the component further comprising a measuring unit to make an optical measurement relating to the orientation of said state, wherein said controller comprises voltage source coupled to electrical contacts configured to apply a modulated electric field across said quantum dot, wherein the modulation is faster than the decay time of said neutral exciton state.

Abstract: An optical flip-flop comprises first (102) and second (104) flip-flop elements arranged to respectively provide first (output 1) and second (output 3) optical outputs. Each output is in one of a plurality of states, wherein switching the output from a relatively high power state to a relatively low power state has an associated falling edge transition time, and switching the output from a relatively low power state to a relatively high power state has an associated rising edge transition time. The rising edge transition time is greater than the falling edge transition time.

Abstract: A system and method is provided for a source for a heralded single photon comprising a correlated photon-pair generator that provides bursts of multiple photon pairs that may be odd or even in number of pairs, one of each pair having a first but not a second characteristic and the other of each pair having the second but not the first characteristic; a first optical path for photons of pairs having the first characteristic; a second optical path for photons of pairs having the second characteristic; a two-photon absorber in the first optical path that, for each burst of photons, reduces the number of first characteristic photons in the first path to zero or one, depending on whether the number of photon pairs in the burst is even or odd; a photon detector in the second path having a heralding signal output to indicate when the number of photons in the burst is odd; and an optical switch coupled to the output of the second optical path and connected to operate in response to the heralding signal.

Abstract: Disclosed herein are atom phase-controlled double rephasing-based quantum memory and a double-rephased photon echo method therefor. The atom phase-controlled double rephasing-based quantum memory includes an optical medium and an optical pulse generation unit. The optical medium has three energy levels (|1>, |2> and |3>), receives one or more optical pulses from an optical pulse generation unit, and generates output light that satisfies phase matching conditions. The optical pulse generation unit generates at least five optical pulses that resonate among the energy levels of the optical medium.

Abstract: Data integrity methods are disclosed for quantum computational plasmonic information representation and processing systems. Also disclosed are methods of saving energy in such applications. Also disclosed are methods of monitoring such applications.

Abstract: There is provided a new architecture for all-optical logic architecture. In this architecture the gate is partitioned into a linear front-end followed by a nonlinear back-end. The logic calculation is practically performed within the linear stage, easing the requirements placed on the non-linear part and thus reducing the gate complexity. The new structures provide flexibility and improved performance for the all-optical logic. The proposed scheme may be integrated optics/electronics. An important additional attribute of our all-optical logic family is reconfigurability, i.e. the ability of the hardware architecture or devices to rapidly alter the functionalities of its components and the interconnection between them as needed.

Abstract: A passive all optical polarization switch and apparatus and methods for implementing logical operations using the switch is provided. The switch converts a first polarized beam having a polarization angle equals to or nearly equals to ±45 degrees into a beam equal to or nearly equal to the vertical component of the first polarized beam. The switch converts a second polarized beam having a polarization angle equals to or nearly equals to ±45 degrees into a beam equal to or nearly equal to the horizontal component of the second polarized beam. The switch combines the vertical component of the first polarized beam and the horizontal component of the second polarized beam to produce an output polarized beam. The switch is used to implement all optical polarization logic gates.

Abstract: A system and method for the controlled generation, manipulation, and conversion of individual photons in and for a quantum computing environment or a quantum communication environment are provided. Systems and methods for doubling a single photon in a first propagation mode into two new photons in one or two new propagation modes, combining two photons in one or two propagation modes into a single photon of a single propagation mode, and implementing a pi phase shift on a two-photon state but not on the one-photon state in a fully controlled, consistent, and repeatable fashion are also provided, as well as a source of individual photons having clearly defined and fully controllable properties. Embodiments of the above allow for generation and conversion operations that are up to 100% efficient. The generation, conversion, combination, and phase shifting operations are preferably carried out inside a non-linear ?3 material of a predetermined length.

Abstract: A system, method, and apparatus for delayed optical logic gates based on slow light and enhanced nondegenerate four-wave mixing processes, where a single or multiple delayed optical routers are utilized for dark resonance interactions in which two-color lasers interact with a three-level nonlinear optical medium comprised of two ground states and one excited state through the nondegenerate four-wave mixing processes. The delayed optical logic mechanism is based on combination of single or multiple dark resonance-induced two-photon coherence conversion via slow light phenomenon. The two-photon coherence induced on the ground states is optically detected via nondegenerate four-wave mixing processes. The nondegenerate four-wave mixing generation is enhanced owing to dark resonance or electromagnetically induced transparency.

Abstract: A quantum bit computation method includes operating a two-quantum-bit gate on quantum bits of a first physical system and a second physical system, second energy states of second physical systems except for the first physical system and the second physical system do not change, three energy states being represented by |0>, |1> and |3>, the two energy states being represented by |2> and |4>, energies of |2> and |4> being higher than energies of |0>, |1> and |3>, a transition frequency between |3> and |2> being equal to the resonance frequency, |0> and |1> representing quantum bits, flipping quantum bits of first physical systems after operating the two-quantum-bit gate, executing no operations by a time equal to a time for operating the two-quantum-bit gate, after flipping the quantum bits, and again flipping the quantum bits of the first physical systems after executing no operations.

Abstract: According to one embodiment, a quantum computer includes a crystal, an optical resonator, and a light source. A host crystal included in the crystal satisfying three conditions a first condition that maximum phonon energy of the host crystal is low, and so that a homogenous broadening of a 3F3(1) level of the Pr3+ ion resulting from relaxation due to phonon emission is smaller than respective hyperfine splits of a 3H4(1) level and the 3F3(1) level of the Pr3+ ion, a second condition that a site of the Pr3+ ion does not have inversion symmetry, and the Pr3+ ion has a Stark level in which the 3H4(1) level and the 3F3(1) level of the Pr3+ ion are not degenerate, and a third condition that each atom in the host crystal has no electronic magnetic moment.

Abstract: Logical operations are implemented using polarization-based logic level representation. An input polarized beam is split into a first beam and a second beam. The first beam is polarized at a first relative polarization angle and the second beam is polarized at a second relative polarization angle. The ratio of the amplitudes of two perpendicular polarization components of the input polarized beam is one or nearly one and the difference between the first relative polarization angle and the second relative polarization angle is 180 degrees or nearly 180 degrees. The relative polarization angle of the input polarized beam equals or nearly equals either the first relative polarization angle or the second relative polarization angle.

Abstract: Various embodiments of the present invention are directed to arbitration systems and methods. In one embodiment, an arbitration system comprises a loop-shaped arbitration waveguide (602), a loop-shaped hungry waveguide (603), and a loop-shaped broadcast waveguide (604). The arbitration, hungry, and broadcast waveguides optically coupled to a home node and a number of requesting nodes. The arbitration waveguide transmits tokens injected by the home node. A token extracted by a requesting node grants the node access to a resource for the duration or length of the token. The hungry waveguide transmits light injected by the home node. A requesting node in a hungry state extracts the light from the hungry waveguide. The broadcast waveguide transmits light injected by the home node such that the light indicates to requesting nodes not in the hungry state to stop extracting tokens from the arbitration waveguide.

Abstract: An operating method for stimulated Raman adiabatic passage to change probability amplitude in a three-level system including states of |0>, |1> and |e>, includes the following two steps. One is to direct a first laser beam and a second laser beam which have frequencies in the vicinity of resonance frequencies corresponding to energy differences between |0> and |e> and between |1> and |e>, respectively. The other is to change temporally two-photon detuning to be a difference between first detuning and second detuning. The first detuning is a difference between a first energy difference and a frequency of the first laser beam. The first energy difference is a difference between energy of |0> and energy of |e>. The second detuning is a difference between a second energy difference and a frequency of the second laser beam. The second energy difference is a difference between energy of |1> and energy of |e>.

Abstract: Improved optical vector matrix multipliers are disclosed. The multipliers comprise: a plurality of light sources, each operable to radiate light of intensity ui; fan-out optics arranged to expand the light radiated by the light sources in one dimension; a spatial light modulator comprising a plurality of light modulating zones, each zone receiving light from one of the light sources and being operable to modulate the intensity of said received light by a factor of vij; and fan-in optics arranged to focus the modulated light onto a plurality of light detectors. The fan out optics, spatial light modulator, and fan-in optics are arranged such that an intensity of light proportional to ? i ? ? u i ? v ij is received at each light detector; and the fan-out optics comprise guided-wave optical components. Specific embodiments are disclosed in which the fanout optics comprise optical splitters, or a partially guiding wedge prism.

Abstract: A method and apparatus (70) are provided for creating an entanglement between two qubits situated in spaced nodes (71, 72) and coupled by an optical channel (75). One node (71) supports a plurality of qubits (73) and is arranged to pass a respective light field through each qubit and on into the optical channel (75), so as to produce a train (78) of closely-spaced light fields on the optical channel (75). The other node (72) supports a target qubit (74) and is arranged to receive the light-field train (78), to allow each successive light field to pass through, and potentially interact with, the target qubit (74) while the latter remains un-entangled, and to thereafter measure each light field to determine whether the latter has been successfully entangled. Upon the second node (72) determining that the target qubit (74) has become entangled, it inhibits the interaction of further light fields with the target qubit.

Abstract: A quantum bit computation method includes operating a two-quantum-bit gate on quantum bits of a first physical system and a second physical system, second energy states of second physical systems except for the first physical system and the second physical system do not change, three energy states being represented by |0>, |1> and |3>, the two energy states being represented by |2> and |4>, energies of |2> and |4> being higher than energies of |0>, |1> and |3>, a transition frequency between |3> and |2> being equal to the resonance frequency, |0> and |1> representing quantum bits, flipping quantum bits of first physical systems after operating the two-quantum-bit gate, executing no operations by a time equal to a time for operating the two-quantum-bit gate, after flipping the quantum bits, and again flipping the quantum bits of the first physical systems after executing no operations.