The present invention relates to a method and an apparatus for quantum key distribution according to a continuous-variable quantum key distribution protocol, which distributes the quantum key in a reverse post-processing manner and, after photon sub traction at a receiver (Bob), detects bit information from a received quantum state to calculate and share the quantum key, such that security can be further enhanced and a cryptographic key generation rate can be increased since the cryptographic key is not exposed to an attacker (Eve).

The present invention relates to a method and an apparatus for quantum key distribution according to a continuous-variable quantum key distribution protocol, which distributes the quantum key in a reverse post-processing manner and, after photon sub traction at a receiver (Bob), detects bit information from a received quantum state to calculate and share the quantum key, such that security can be further enhanced and a cryptographic key generation rate can be increased since the cryptographic key is not exposed to an attacker (Eve).

Systems and methods are disclosed for preparing and evolving atomic defects in diamond. Silicon vacancy spins may be cooled to temperatures equal to or below 500 mK to reduce the influence of phonons. The cooling, manipulation, and observation systems may be designed to minimize added heat into the system. A CPMG sequence may be applied to extend coherence times. Coherence times may be extended, for example, to 13 ms.

Systems and methods are disclosed for preparing and evolving atomic defects in diamond. Silicon vacancy spins may be cooled to temperatures equal to or below 500 mK to reduce the influence of phonons. The cooling, manipulation, and observation systems may be designed to minimize added heat into the system. A CPMG sequence may be applied to extend coherence times. Coherence times may be extended, for example, to 13 ms.

Systems, computer-implemented methods, and/or computer program products that can facilitate target qubit decoupling in an echoed cross-resonance gate are provided. According to an embodiment, a computer-implemented method can comprise receiving, by a system operatively coupled to a processor, both a cross-resonance pulse and a decoupling pulse at a target qubit. The cross-resonance pulse propagates to the target qubit via a control qubit. The computer-implemented method can further comprise receiving, by the system, a state inversion pulse at the control qubit. The computer-implemented method can further comprise receiving, by the system, both a phase-inverted cross-resonance pulse and a phase-inverted decoupling pulse at the target qubit. The phase-inverted cross-resonance pulse propagates to the target qubit via the control qubit.

Systems, computer-implemented methods, and/or computer program products that can facilitate target qubit decoupling in an echoed cross-resonance gate are provided. According to an embodiment, a computer-implemented method can comprise receiving, by a system operatively coupled to a processor, both a cross-resonance pulse and a decoupling pulse at a target qubit. The cross-resonance pulse propagates to the target qubit via a control qubit. The computer-implemented method can further comprise receiving, by the system, a state inversion pulse at the control qubit. The computer-implemented method can further comprise receiving, by the system, both a phase-inverted cross-resonance pulse and a phase-inverted decoupling pulse at the target qubit. The phase-inverted cross-resonance pulse propagates to the target qubit via the control qubit.

A millimeter-wave communication device includes a coupler, Radio-Frequency (RF) circuitry and a composite right/left-handed metamaterial assembly. The coupler is configured to connect to a waveguide, the waveguide being transmissive at millimeter-wave frequencies and having a given dispersion characteristic over a predefined band of the millimeter-wave frequencies. The RF circuitry is configured to transmit a millimeter-wave signal into the waveguide via the coupler, or to receive a millimeter-wave signal from the waveguide via the coupler, and to process the millimeter-wave signal. The composite right/left-handed metamaterial assembly is formed to apply to the millimeter-wave signal, or to an Intermediate-Frequency (IF) signal corresponding to the millimeter-wave signal, a dispersion compensation that compensates for at least part of the dispersion characteristic of the waveguide over the predefined band.

The transmission device of the present embodiment includes a waveguide unit which transmits a terahertz-wave signal, and a plurality of ports provided around the waveguide unit and each composed of a waveguide and a planar lens, the waveguide unit and the ports being integrated on a planar substrate with dielectric properties. The planar lens diffuses, in an arcuate shape, a terahertz-wave signal by a reflective index set by a staggering arrangement of first through-holes, transmits the diffused terahertz-wave signal to the waveguide unit in parallel, or focuses a terahertz-wave signal which is transmitted in parallel through the waveguide unit. A beam splitter transmits a terahertz-wave signal, which is transmitted in parallel from a first planar lens, to a second planar lens, by reflection or transmission by a refractive index set by a grid arrangement of second through-holes.

A system includes a transmission unit, a reception unit, and a lens unit and is placed in a passage, wherein in a case where a first plane that intersects a forward direction of the passage and is a surface of an object, and a second plane that intersects the forward direction of the passage, includes the lens unit, and is at a position different from a position of the first plane are set, a first area to which a terahertz wave from the transmission unit reflected from the first plane is emitted and the lens unit are disposed at positions different from each other on the second plane.

A system includes a transmission unit, a reception unit, and a lens unit and is placed in a passage, wherein in a case where a first plane that intersects a forward direction of the passage and is a surface of an object, and a second plane that intersects the forward direction of the passage, includes the lens unit, and is at a position different from a position of the first plane are set, a first area to which a terahertz wave from the transmission unit reflected from the first plane is emitted and the lens unit are disposed at positions different from each other on the second plane.