A photonic control system is disclosed for optical control of superconducting RF structures. The photonic control system includes an optical light source transmitter including a laser and an RF driver supplying an optical signal. An optical fiber assembly is optically coupled to the optical light source transmitter. A photodetector is optically coupled to the optical light source transmitter via the optical fiber. The photodetector converts the optical signal to an RF signal. A photonically controlled superconducting RF structure such as a qubit or a readout resonator receives the RF signal from the photodetector.

A photonic control system is disclosed for optical control of superconducting RF structures. The photonic control system includes an optical light source transmitter including a laser and an RF driver supplying an optical signal. An optical fiber assembly is optically coupled to the optical light source transmitter. A photodetector is optically coupled to the optical light source transmitter via the optical fiber. The photodetector converts the optical signal to an RF signal. A photonically controlled superconducting RF structure such as a qubit or a readout resonator receives the RF signal from the photodetector.

A technique relates to configuring a superconducting router. The superconducting router is operated in a first mode. Ports are configured to be in reflection in the first mode in order to reflect a signal. The superconducting router is operated in a second mode. A given pair of the ports is connected together and in transmission in the second mode, such that the signal is permitted to pass between the given pair of the ports.

A technique relates to configuring a superconducting router. The superconducting router is operated in a first mode. Ports are configured to be in reflection in the first mode in order to reflect a signal. The superconducting router is operated in a second mode. A given pair of the ports is connected together and in transmission in the second mode, such that the signal is permitted to pass between the given pair of the ports.

Methods and apparatus for optimizing a quantum circuit. In one aspect, a method includes identifying one or more sequences of operations in the quantum circuit that un-compute respective qubits on which the quantum circuit operates; generating an adjusted quantum circuit, comprising, for each identified sequence of operations in the quantum circuit, replacing the sequence of operations with an X basis measurement and a classically-controlled phase correction operation, wherein a result of the X basis measurement acts as a control for the classically-controlled correction phase operation; and executing the adjusted quantum circuit.

Methods and apparatus for optimizing a quantum circuit. In one aspect, a method includes identifying one or more sequences of operations in the quantum circuit that un-compute respective qubits on which the quantum circuit operates; generating an adjusted quantum circuit, comprising, for each identified sequence of operations in the quantum circuit, replacing the sequence of operations with an X basis measurement and a classically-controlled phase correction operation, wherein a result of the X basis measurement acts as a control for the classically-controlled correction phase operation; and executing the adjusted quantum circuit.

A quantum communication method, an apparatus, and a system are provided. The method includes: modulating a first symbol to an i.sup.th direction vector of a first electric wave based on a preset mapping relationship, to obtain a second electric wave; and transmitting the second electric wave, where the first electric wave supports M direction vectors, the i.sup.th direction vector of the first electric wave is one of the M direction vectors of the first electric wave, the first symbol is a symbol corresponding to first data, the i.sup.th direction vector of the first electric wave corresponds to an i.sup.th distribution result, the i.sup.th distribution result is obtained by converting the second electric wave into an energy quantum. The first symbol may be modulated to a direction vector of the first electric wave, and this application is compatible with the conventional technology.

A quantum communication method, an apparatus, and a system are provided. The method includes: modulating a first symbol to an i.sup.th direction vector of a first electric wave based on a preset mapping relationship, to obtain a second electric wave; and transmitting the second electric wave, where the first electric wave supports M direction vectors, the i.sup.th direction vector of the first electric wave is one of the M direction vectors of the first electric wave, the first symbol is a symbol corresponding to first data, the i.sup.th direction vector of the first electric wave corresponds to an i.sup.th distribution result, the i.sup.th distribution result is obtained by converting the second electric wave into an energy quantum. The first symbol may be modulated to a direction vector of the first electric wave, and this application is compatible with the conventional technology.

A degenerate four-wave mixing (DFWM) squeezed light apparatus includes one or more pump beams, a probe beam, a vapor cell, a repump beam, and a detector. The one or more pump beams includes an input power of no greater than about 150 mW. The vapor cell includes an atomic vapor configured to interact with overlapped pump and probe beams to generate an amplified probe beam and a conjugate beam. The repump beam is configured to optically pump the atomic vapor to a ground state and decrease atomic decoherence of the atomic vapor. The detector is configured to measure squeezing due to quantum correlations between the amplified probe beam and the conjugate beam. The one or more pump beams, the probe beam, and the repump beam are configured to generate two-mode squeezed light by DFWM with squeezing of at least 3 dB below shot noise.

Systems and methods of optical restoration include, with a photonic service (14), in an optical network (10, 100), operating between two nodes (A, Z) via an associated optical modem (40) at each node, wherein each modem (40) is capable of supporting variable capacity, C.sub.1, C.sub.2, . . . , C.sub.N where C.sub.1>C.sub.2> . . . >C.sub.N, detecting a fault (16) on a home route of the photonic service (14) while the photonic service (14) operates at a home route capacity C.sub.H, C.sub.H is one of C.sub.1, C.sub.2, . . . , C.sub.N−1; downshifting the photonic service (14) to a restoration route capacity C.sub.R, C.sub.R is one of C.sub.2, C.sub.3 . . . , C.sub.N and C.sub.R<C.sub.H; switching the photonic service (14) from the home route to a restoration route (18) while the photonic service (14) operates at a restoration route capacity C.sub.R; and monitoring the photonic service (14) and copropagating photonic services during operation on the restoration route (18) at the restoration route capacity C.sub.R for an upshift of the photonic service (14).