37 results about "Coherent states" patented technology

One aspect of the present invention is related to a quantum cryptographic scheme comprising at least one sending unit including a physical means of encoding and distributing a raw key in the quadrature components of quantum coherent states that are continuously modulated in phase and amplitude, at least one receiving unit containing a physical means of performing homodyne detection of the quantum coherent states in order to measure the quadrature components of the states, a quantum channel for connecting the sending unit to the receiving unit, a two-way authenticated public channel for transmitting non-secret messages between the sending unit and the receiving unit, a quantum key distribution protocol ensuring that the information tapped by a potential eavesdropper can be estimated from the quantum channel parameters, and a direct or reverse reconciliation protocol that converts the raw continuous data into a common binary key.

The invention discloses a long range CVQKD (Continuous Variable Quantum Key Distribution) method based on a Gaussian-modulationcoherent state. The method includes a step A of continuous variable initial key distribution which includes Gaussianmodulation of initial continuous key data through a coherent state by a sender Alice, long range transmission through an optical channel, demodulation and detection by a receiver Bob, and acquisition of initial continuous key data; and a step B of pre-treatment, error correction and confidentiality enhancement on acquired initial continuous key data by utilizing a data post-treatment algorithm and acquisition of a final binary digit safe key. According to the invention, the safe communication range of a CVQKD system based on the Gaussian-modulationcoherent state can be enlarged to 100-150 km.

A quantum cryptographic protocol is proposed, which uses two-mode coherent states and an M-ary modulation format determined in part by an expanded secret key. The encrypted signal is optically amplifiable, resulting in a polarization independent system that is compatible with the existing WDM communications infrastructure.

The invention provides a high-speed continuous variable quantum key distribution system and a bit frame synchronization method thereof. The bit frame synchronization method comprises the following steps: Step one, a sender generates a set of special data used as a synchronous frame; Step two, the sender sends a coherent state to a receiver through a quantum channel; Step three, the receiver uses a balance homodyne detector to measure the displacement component of the coherent state; Step four, the receiver selects an appropriate alternate voltage determining threshold and a frame synchronization segment determining threshold to determine the synchronous frame according to structure information of the special data acquired through a classical channel in Step one; and Step five, synchronization fails if the receiver does not search the synchronous frame in the specified time, and the receiver needs to adjust the value of the alternate voltage determining threshold and the value of the frame synchronization segment determining threshold and reestablishes communication. According to the invention, the interference of external environmental factors to synchronization signals in the process of quantum key distribution can be effectively overcome, and synchronization between both sides of communication can be realized.

The invention provides a quantum key distribution system and method based on continuous variable measurement equipment independence. The quantum key distribution system comprises a sender Alice and a receiver Bob, and is characterized in that the receiver Bob is connected with a balance homodyne detector BHD through a wavelength division multiplexer WDM; the sender Alice is connected with the balance homodyne detector BHD at Alice and Bob ends; after a continuous wave laser device (LD) passes through an intensity modulator (IM), light pulse is formed by attenuation; Gaussian-modulation encoding of a coherent state is finished after the light pulse is processed by an amplitude modulator (AM) and a phase modulator (PM) under the control of a random number generated by a PC (Personal Computer) machine; then a result is sent to a third party Charlie; generated noises have relatively small influences on the system; influences on a safety key generation speed of the system, caused by forward transmission and backward transmission of a channel can be ignored; and advantages of a metropolitan area network based on a CV-MDIQKD quantum cryptography communication system are very obvious, and a foundation can be laid for commercialized and networked application in the future.

The present invention pertains to the field of electronic design automation (EDA). More particularly, this invention relates to using coherent state among multiple simulation models within an EDA simulation environment. Two related inventions are described. One invention selectively activates certain simulation domains in an electronic design automation (EDA) simulation environment at various times during the simulation of a circuit design and maintains timing synchronization among the various domains. The other invention makes state information accessible to simulation models in an EDA simulation environment without the necessity of simulating data transfers in the simulated circuit design. In various embodiments, the inventions increase efficiency and versatility of a simulation environment.

In the present work, quantum clustering is extended to provide a dynamical approach for data clustering using a time-dependent Schrödinger equation. To expedite computations, we can approximate the time-dependent Hamiltonian formalism by a truncated calculation within a set of Gaussian wave-functions (coherent states) centered around the original points. This allows for analytic evaluation of the time evolution of all such states, opening up the possibility of exploration of relationships among data points through observation of varying dynamical-distances among points and convergence of points into clusters. This formalism may be further supplemented by preprocessing, such as dimensional reduction through singular value decomposition and / or feature filtering. Additionally, the parameters of the analysis can be modified in order to improve the efficiency of the dynamic quantum clustering processes.

The invention discloses a phase compensation implementation method of a continuous variable quantum key distribution system. A sender performs Gaussian modulation on initial continuous key data by using the coherent state and then sends the modulated signals to a receiver through an optical fiber channel; and the receiver performs preprocessing, error corrosion and confidentiality enhancement on the acquired initial continuous key data by using an algorithm based on orthogonal basis expansion so as to acquire the final security key. According to the method, the practical use of the continuous variable quantum cryptography is prompted, and environmental interference and human attack affected by the quantum signals in the quantum communication process can also be effectively suppressed.

A database management and indexing technique provides coherent access to and update of dynamic configuration information stored in a database associated with a multiprocessing environment of an aggregation router. The multiprocessing environment comprises a forwarding engine configured as a computing matrix of processors that operate on packets in a parallel as well as a pipeline fashion. A unique handle, i.e., a virtual common coherency index (VCCI) value, is associated with an interface regardless of whether it is a virtual or a physical interface. When a packet enters the computing matrix, it is classified and assigned a VCCI value based upon the interface over which it is received at or transmitted from the router. The assigned VCCI value is then passed along with the packet to each feature that processes the packet.

A method and apparatus for quantum information processing is disclosed in which logical qubits |0>L and |1>L are respectively encoded by different near orthogonal coherent states |β> and |α>, where <α|β>=0, |α> and |β> being the computational basis states for the qubits, for example, in which logical qubits |0>L and |1>L are respectively encoded by different ones of the vacuum state |0> and a multi-photon optical coherent state |α> which states are the computational basis states for the qubits. This provide an efficient scheme for linear optics quantum processing which is deterministic and for which qubit readout can use homodyne detection which is highly efficient. The invention finds application in quantum computation and quantum communication.

The invention discloses a decoy-state quantum key distribution (QKD) system based on a discrete random phase. The decoy-state quantum key distribution system comprises a light source which adopts a coherent light source, a first phase regulator used for regulating n (n is a positive integer) discrete random coherent-state phase information alpha for encoding, and a QKD encoder used for QKD encoding. According to the distribution system disclosed by the embodiment of the invention, the coherent light source is adopted and the phase regulator is used for regulating the n discrete random coherent-state phase information alpha for QKD encoding, so that the implementation of a decoy-state protocol is simplified, communication safety is guaranteed, and the QKD system is simplified.

The invention provides a continuous random measurement matrix-based continuous variable quantum key distribution method. The method comprises the following steps of first, Gaussian modulation of a coherent state by a sending end, wherein the sending end prepares true random numbers of Gaussian distribution and prepares the coherent state, and encodes the coherent state through strength and a phasemodulator according to an element of a Gaussian random number set; second, transmission of a Gaussian signal, wherein the sending end transmits the encoded coherent state signal to a receiving end through a quantum channel; third, demodulation of a continuous random measurement matrix by the receiving end, wherein the receiving end prepares a plurality of binary variables that are distributed continuously and randomly; and fourth, data consultation and privacy amplification. Through adoption of the method, matrix comparison is prevented so that some original data strings are not discarded, further, the method is easy to realize in the prior art. Due to use of continuously distributed phase angles, requirements on performance of a digital-analog converter and a phase modulator are relatively lowered, so that engineering is easy to realize.

The invention discloses a novel continuous variable quantum key distribution method based on machine learning. The method comprises: a sending end preparing a modulation coherent state with a known mark and sends the modulation coherent state to a receiving end; the receiving end obtaining a measurement result; extracting features and dividing a training set and a test set; using the training setto train a classifier to obtain a training classifier, and using the test set to test and obtain a quantum classifier; the sending end preparing the secret key into a modulation coherent state and sending the modulation coherent state to the receiving end; the receiving end receiving the modulation coherent state and obtains a measurement result; the receiving end extracting characteristics of themeasurement result, and using a quantum classifier to predict and obtain category marks; and repeating the above steps until the sending end and the receiving end share the original key, and ending the distribution. The method has the advantages of excellent performance, less occupied resources and better real-time performance, and is also suitable for the existing continuous variable quantum keydistribution system.

The invention relates to a four-state modulation continuous variable quantum key distribution data coordination method and system, and the method comprises the steps: enabling a key to be modulated toa coherent state, and enabling the coherent state to be transmitted to a receiving end through a quantum channel; acquiring a measurement result by utilizing a balance homodyne detector, further acquiring a normalization result of a coherent state, determining a filtering function value, judging whether each bit of key is reserved or not, if so, marking freezing bit information at the position ofthe bit of key, and sending a key information segment in the reserved key to a sending end through a classical channel; Judging whether the quantum channel is safe or not, and sending judgment information to a receiving end; If the judgment information is quantum channel security, freezing bit information of the key information except the key information segment is coded by a system Polar code and then sent to a sending end; And the freezing bit information is decoded by a Polar code of the system, key information corresponding to the freezing bit information is obtained, and a final securitykey is obtained through encryption amplification. According to the method, the data coordination efficiency can be improved, the security key can be effectively extracted, and the equipment complexity can be reduced.

The invention provides an encoding-based continuous variable quantum key distribution method and system. According to the method and system, a transmitting end performs coherent state preparation, andencodes a coherent state according to a continuous variable true random number of Gaussian distribution; encoded coherent state signals are transmitted to a receiving end through a quantum channel, so that the receiving end performs coherent state detection; the receiving end randomly and selectively publicizes a detection result of a part of a position and a measurement base, so that the transmitting end can perform base comparison and the data evaluation, the method restarts when a key rate is smaller than or equal to zero; the receiving end publicizes the detection result of the remainingposition, and the transmitting end judges a measurement base adopted by the receiving end according to the detection result of the remaining position; the receiving end and the transmitting end adoptcorresponding base information as their respective keys; and the receiving end and the transmitting end negotiate with each other and perform privacy amplification enhancement operation by means of aclassical channel. With the method and system of the invention adopted, long-distance secure communication under a high over-noise condition can be realized, and a requirement for negotiation efficiency is lower. Except a decoding step, all steps are consistent with an existing continuous variable quantum key distribution protocol, and therefore, the fused application of the method and the continuous variable quantum key distribution protocol can be implemented with easiness.

The invention relates to an ultra-resolution and ultra-sensitivity ranging system based on an entangled coherent state. The system consists of a quantum state preparation system, a emit and receive system, a quantum state coherent detection system, and a computer comprehensive analysis system, wherein a quantum source generates a coherent superposed laser quantum state, a laser generates a coherent laser quantum state, the above two laser quantum states are interfered by a first 50:50 beam splitter so as to obtain an entangled coherent state, a detection signal is emitted through an optical emission system so as to irradiate a target, an echo signal is received through an optical receiving system, the echo signal and a local oscillation signal are interfered by a second 50:50 beam splitter, the interference signal carries distance information of the target, the interference signal is converted into a binary output electric signal, the electric signal is analyzed comprehensively by thecomputer comprehensive analysis system, so as to offer distance information of the target. Through adoption of the system, a goal of ultra-resolution and ultra-sensitivity measurement of a signal is achieved.

The invention discloses a distributed information weighted coherent state filtering method for a sensor network, belonging to sensor information fusion technology, which relates to a distributed nonlinear state estimation problem of the sensor network. Firstly, a square root volume rule is used to obtain the prediction information vector and the square root information matrix of each node to the target state. Then, each node updates local state information by weighted local prediction information and observation information vector, updates local square root information matrix by weighted localprediction information and observation information matrix, and combines matrix triangular decomposition. Finally, the information consistency of the whole network is achieved by using the weighted consistency of the neighboring nodes, and the estimation of the target state is completed. This method improves the convergence rate of the state estimation in the network, enhances the numerical stability of the algorithm, and improves the accuracy of the state estimation of the target under the condition of limited energy.

The invention provides a high-speed continuous variable quantum key distribution system and a bit frame synchronization method thereof. The bit frame synchronization method comprises the following steps: Step one, a sender generates a set of special data used as a synchronous frame; Step two, the sender sends a coherent state to a receiver through a quantum channel; Step three, the receiver uses a balance homodyne detector to measure the displacement component of the coherent state; Step four, the receiver selects an appropriate alternate voltage determining threshold and a frame synchronization segment determining threshold to determine the synchronous frame according to structure information of the special data acquired through a classical channel in Step one; and Step five, synchronization fails if the receiver does not search the synchronous frame in the specified time, and the receiver needs to adjust the value of the alternate voltage determining threshold and the value of the frame synchronization segment determining threshold and reestablishes communication. According to the invention, the interference of external environmental factors to synchronization signals in the process of quantum key distribution can be effectively overcome, and synchronization between both sides of communication can be realized.

In this statement, realization of “Non-volatile molecular multiple quantum bit (NVQB)” is described. NVQB is the long-term macroscopic time scale analogue of MMQB. To realize NVQB, while inverted population of the gas is kept, entanglement generation and coherent state keeping must be carried out for a long-term quantum computation. Operating principle of molecular quantum computer is entanglement generation among huge-number of molecular ro-vibronic eigenstates by emission and absorption of photons due to the Fermi golden rule. Each single photon generated in induced absorption and induced emission sews many quantum states of many molecules by the Fermi golden rule. This results entanglement. When NVQB is realized, NVQB is not only used as “quantum storage device” up to 2Na, but also NVQB itself makes practical reasonable commercial molecular quantum computer be realized at once. NVQB is an alias of long-term successfully operating molecular quantum computer.

The invention discloses a continuous variable quantum key distribution method based on a super-Nyquist technology. The method comprises the steps that a sender performs Gaussian modulation on signal light through a coherent state; the sender carries out up-sampling on the signal light of the sender, converts the signal light into a super-Nyquist signal and transmits the super-Nyquist signal; and the receiving end processes the received signal so as to obtain data sent by the sender. According to the continuous variable quantum key distribution method based on a super-Nyquist technology, a super-Nyquist transmission technology is introduced, the traditional Nyquist rate limit is broken through, and for the problem of intersymbol interference artificially introduced by Nyquist transmission,data post-processing technologies such as cyclic prefix addition, equalization technology and iterative detection are adopted, so that the influence of the intersymbol interference on the system security is effectively eliminated, and the frequency band utilization rate and the channel capacity of the system are improved; and the method is high in reliability and good in safety.

The invention discloses an N00N state preparation device and belongs to the field of N00N state preparation with an aim to solve problems that an existing N00N state preparation device is complicatedin structure and poor in expansibility since only N00N states with a specific number of photons can be prepared. The N00N state preparation device comprises a laser, a polarizer, a first 50:50 beam splitter prism, a frequency doubling crystal, a long wave filter, a down-conversion crystal, a short wave filter, a first reflector, a second reflector, an attenuation slice, a phase shifter and a second 50:50 beam splitter prism; phase and light-adjustable coherent beam emitted by the phase shifter are reflected via the first reflector, output compressed vacuum beam interferes at the second 50:50 beam splitter prism, and N00N state laser beam is obtained. The N00N state preparation device is applied to the field of quantum information.

In this statement, realization of “Non-volatile molecular multiple quantum bit (NVQB)” is described. NVQB is the long-term macroscopic time scale analog of MMQB. To realize NVQB, while inverted population of the gas is kept, entanglement generation and coherent state keeping must be carried out for a long-term quantum computation. Operating principle of molecular quantum computer is entanglement generation among huge-number of molecular ro-vibronic eigenstates by emission and absorption of photons due to the Fermi golden rule. Each single photon generated in induced absorption and induced emission sews many quantum states of many molecules by the Fermi golden rule. This results entanglement. When NVQB is realized, NVQB is not only used as “quantum storage device” up to 2Na, but also NVQB itself makes practical reasonable commercial molecular quantum computer be realized at once. NVQB is an alias of long-term successfully operating molecular quantum computer.