A quantum communications system may include a transmitter node, a receiver node, and a quantum communications channel coupling the transmitter node and receiver node. The transmitter node may include a pulse transmitter, a pulse divider downstream from the pulse transmitter, and at least one first waveplate upstream from the pulse divider and configured to alter a polarization state of pulses travelling therethrough. The receiver node may include at least one second waveplate being a conjugate of the at least one first waveplate, a pulse recombiner upstream from the at least one second waveplate, and a pulse receiver downstream from the at least one second waveplate.

A first node of a network includes a quantum receiver, a classical transceiver, and an initial-key generator that cooperate with a second node of the network to receive an initial key via the quantum receiver. The first node includes a key-series generator that (i) decrypts, with the initial key, a first encrypted key of a series of encrypted keys to generate a first unencrypted key of a respective series of unencrypted keys and (ii) decrypts each subsequent encrypted key of the series of encrypted keys with a preceding unencrypted key of the series of unencrypted keys to generate a subsequent unencrypted key of the series of unencrypted keys. The first node includes one or both of a decryptor and an encryptor. The decryptor decrypts encrypted data using a last unencrypted key of the series of unencrypted keys. The encryptor encrypts unencrypted data using the last unencrypted key.

A communication system comprising n transmitters and a receiver, where n is an integer of at least 2, each of said n transmitters comprising a light source and an encoder such that each transmitter is adapted to output an encoded pulse of light, said receiver comprising a first element, the system further comprising a timing circuit, the timing circuit being configured to synchronize the encoded pulses output by the transmitters such that interference between a light pulse sent from the first transmitter and a light pulse from the second transmitter, interfere at the first element, each transmitter further comprising a suppressing element adapted to stop light exiting one of the transmitters such that the system is switchable between a first operation mode where two transmitters output encoded pulses and where both pulses interfere at the interference element and a second mode of operation where just one transmitter transmits light pulses to said receiver, the suppressing element being controlled to stop light exiting the other transmitter.

A method of qubits, a room temperature quantum computing and a system including a controller, a readout, a resistor and a storage are disclosed. The shape and area of each qubits and the pattern of qubit array may be defined by a pattern on a mask simultaneously to control correlations among qubits. The configuration of qubit correlation may be designed three-dimensionally by stacking layers including arrays of qubits. The external generator may be included in another layer stacked with the layers including the arrays of qubits. The qubit may comprise a band structure having a spin-less ground state and a first excited state with spin. The first excited state may not be split for a retention time even under the external field which can influence a spin. The configuration of qubit correlations may be tuned by considering this retention time and an error correction code in quantum computation.

A hyper-entanglement photon server (i.e., hub) employs non-degenerate frequencies input as entangled photon pairs into a beam splitter. The beam splitter splits probability amplitudes into two sets of bunched superposition states plus two sets of anti-bunched superposition states. The amplitudes pass through identical Lyot filters and then either enter a polarization beam splitter, where the bunched and anti-bunched states switch identities, or merely advance unchanged to awaiting users at two distinct and spatially-displaced positions (i.e., spokes). The Lyot filters change the output amplitudes from rotationally invariant superpositions of generalized Bell States to rotationally non-invariant superpositions of generalized Bell states. All hubs and spokes pre-share operating key material (a security method called KCQ) that may be continually updated by shared stream ciphers seeded by fresh key material engendered by hub-to-spoke quantum communication.

An identity authentication method for a quantum key distribution process includes selecting, by a sender, preparation bases of an identity authentication bit string in accordance with a preset basis vector selection rule; sending, by a sender, quantum states of the identity authentication bit string and quantum states of a randomly generated key bit string by using different wavelengths. The identity authentication bit string is interleaved in the key bit string at a random position and with a random length. The method further includes measuring, by a receiver, the received quantum states in the quantum state information in accordance with the different wavelengths and measurement bases selected according to the preset basis vector selection rule to obtain identity authentication information from the measurement of the identity authentication bit string; and determining, by the receiver, whether the identity authentication information obtained through the measurement corresponds with the preset basis vector selection rule.

A node may receive, from a quantum key-distribution (QKD) device, a first message that includes an identifier associated with a key. The node may send, to another node, a second message that includes the identifier and a request to perform at least one task. A node may receive, from the other node, a third message that includes information associated with performance of the at least one task by the other node and information indicating a time of performance. The node may receive, from the QKD device, a fourth message that includes the key and information indicating a time window associated with the quantum key; wherein the fourth message is received after expiration of the time window. The node may process, based on the fourth message, the third message to determine whether the third message is valid and thereby cause one or more actions to be performed.

A quantum key distribution system includes a quantum security key management (QSKM) device, a plurality of quantum security key distribution (QSKD) devices, and a quantum security key service (QSKS) device. The QSKD device splits an identity-based system private key into a plurality of system sub-private keys, and distributes the plurality of system sub-private keys to a corresponding number of the QSKD devices. The QSKS device forwards a request for acquiring an authorized private key from a first QSKD device to a predetermined number of second QSKD devices. The predetermined number of second QSKD devices each generate an identity-based authorized sub-private key from the system sub-private key. The first QSKD device acquires, from the predetermined number of second QSKD devices, the identity-based authorized sub-private keys, and reconstructs an identity-based authorized private key based on the identity-based authorized sub-private keys.

Embodiments of this application relate to the field of communications technologies. The embodiments of this application are applicable to a centralized management and control network. A centralized controller obtains Z service requests, globally determines, based on an identifier of a source service node and an identifier of a destination service node that are corresponding to each of the Z service requests, a quantum key consumption parameter, and topology information of key nodes in the centralized management and control network, globally optimal key relay instructions corresponding to G service requests, and further delivers the key relay instructions corresponding to the G service requests to key nodes corresponding to the key relay instructions, so that the key nodes perform quantum key relay based on the key relay instructions, to generate a shared quantum key between the source key node and the destination key node.

A method for distributing a quantum digital key is described. The method comprises the use of an optical broadband source to generate an optical broadband signal. The optical broadband signal may be transmitted from a first party to a second party through an optical communication channel. The optical broadband signal may be transmitted with a low brightness, such as less than one photon/(sec-Hz), so as to be immune from passive attacks. Furthermore, a method for detecting the presence of active attackers is described. The method may comprise a coincidence measurement configured to measure the level of entanglement between an optical detection signal and an optical idler signal.