Kabushiki Kaisha Toshiba

Kouichi Ichimura

Hayato Goto

Satoshi Nakamura

Kazushige Yamamoto

Nobuhiro Gemma

Noritsugu Shiokawa

Mamiko Kujiraoka

Masayuki Nakamoto

Satoshi Mitsugi

Kenji Ohkuma

Kentaro Torii

Mikio Fujii

Hironori Uchikawa

Toshiro Hiraoka

Tetsufumi Tanamoto

Masao Obama

Hiroshi Masumoto

According to one embodiment, an information processing device includes a qubit pair structure body including a plurality of qubit pairs. The qubit pairs are arranged in m rows and n columns. The qubit pairs include first, and second qubit pairs, and first to sixth adjacent qubit pairs. The qubit pair structure body includes first to eighth spin chains. The first and fifth spin chains include a first eigenenergy, and not include the second, third, and fourth eigenenergies. The second and sixth spin chains include a second eigenenergy, and not include the first, third, and fourth eigenenergies. The third and seventh spin chains include a third eigenenergy, and not include the first, second, and fourth eigenenergies. The fourth spin chain and the eighth spin chain include a fourth eigenenergy, not include the first, second, and third eigenenergies. The first to fourth eigenenergies are different from each other.

Information processing device and information processing method

According to one embodiment, an optical device includes a first mirror, a second mirror, and a first member. The first mirror has a first planar surface. The second mirror is spaced from the first mirror in a first direction crossing the first planar surface. The second mirror has a concave surface including a first region and a second region around the first region. First distance between the first region and the first planar surface in the first direction is longer than second distance between the second region and the first planar surface in the first direction. The first distance is half or less of curvature radius of the concave surface. The first member is light transmissive and solid. The first member includes a first portion provided between the first mirror and the second mirror. The first portion is in contact with the first planar surface and the concave surface.

Optical device

According to one embodiment, a cavity with a cavity mode which is coupled to physical systems includes a spherical mirror and a plane mirror. The spherical mirror is provided at a birefringent crystal including the physical systems. The plane mirror is provided at the birefringent crystal opposite to the spherical mirror. The birefringent crystal has a first refractive index to light polarized in a first direction parallel to a polarization direction of the cavity mode on an optical axis of the cavity and a second refractive index to light polarized in a second direction parallel to the optical axis, the second refractive index being different from the first refractive index. A cavity length of the cavity and a mode waist radius of the cavity mode satisfy a specific condition.

Cavity and quantum computer

According to an embodiment, a quantum computer includes first physical systems provided in a cavity, a second physical system provided in the cavity, and a light source unit. The first physical systems include a transition coupled to a common cavity mode of the cavity. The second physical system includes a first transition coupled to the common cavity mode and a second transition. The light source unit generates a first and a second light beam to manipulate two of the first physical systems and generates a third light beam that resonates with the second transition. The third light beam is radiated to the second physical system during a period when the first and the second light beam are simultaneously radiated to the two first physical systems.

Quantum computer and quantum computing method

According to an embodiment, a quantum computer includes physical systems X, a physical system Yand a light source unit. The physical systems Xand the physical system Yare provided in a cavity. Each physical system Xincludes states |0&#x3e;, |1&#x3e;, |2&#x3e;and |e&#x3e;, the states |0&#x3e;and |1&#x3e;being used for a qubit, a |2&#x3e;-|e&#x3e;transition being resonant with a cavity mode of the cavity. The physical system Yincludes states |2&#x3e;'and |e&#x3e;&#x2032;, a |2&#x3e;&#x2032;-|e&#x3e;&#x2032;transition being resonant with the cavity mode. The light source unit applies laser beams to the cavity to manipulate states of two of physical systems X, the laser beams including a laser beam for collecting population in the state |2&#x3e;&#x2032;in the |2&#x3e;&#x2032;-|e&#x3e;&#x2032;transition.

According to one embodiment, an acousto-optic modulator includes an acousto-optic medium and a piezoelectric transducer. The acousto-optic medium has a configuration of a hexahedron. The acousto-optic medium has surfaces D, E, F, G and H. The piezoelectric transducer is provided on a surface C of the acousto-optic medium. The surface D opposes the surface C and has respective four sides shared by the surfaces E, F, G and H. Four angles defined between the surface D and the surfaces E, F G and H each is other than 90&#xb0;. At least one of eight angles defined between each pair of the surfaces C, E, F, G and H is other than 90&#xb0;. The each pair has one shared side.

Acousto-optic modulator

According to one embodiment, an acousto-optic modulator includes an acousto-optic medium and a piezoelectric transducer. The acousto-optic medium has a configuration of a hexahedron. The acousto-optic medium has surfaces D, E, F, G and H. The piezoelectric transducer is provided on a surface C of the acousto-optic medium. The surface D opposes the surface C and has respective four sides shared by the surfaces E, F, G and H. Four angles defined between the surface D and the surfaces E, F, G and H each is other than 90&#xb0;. At least one of eight angles defined between each pair of the surfaces C, E, F, G and H is other than 90&#xb0;. The each pair has one shared side.

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 aF(1) level of the Prion resulting from relaxation due to phonon emission is smaller than respective hyperfine splits of aH(1) level and theF(1) level of the Prion, a second condition that a site of the Prion does not have inversion symmetry, and the Prion has a Stark level in which theH(1) level and theF(1) level of the Prion are not degenerate, and a third condition that each atom in the host crystal has no electronic magnetic moment.

Quantum computer and quantum memory

According to one embodiment, a decoding apparatus includes first and second acquisition units, a holding unit, a calculation unit, and a decision unit. The first acquisition unit acquires first measurement values of measurements performed to measure an eigenvalue of an encoded Z operator to a first encoded qubit of the two encoded qubits. The second acquisition unit acquires second measurement values of measurements performed to measure an eigenvalue of an encoded X operator to a second encoded qubit of the two encoded qubits. The holding unit holds error probabilities for the first measurement values and the second measurement values. The calculation unit calculates probabilities for measurement values of an encoded Bell measurement by using the first measurement values, the second measurement values, and the error probabilities. The decision unit decides measurement values of the encoded Bell measurement, based on the calculated probabilities.

Decoding apparatus, decoding method, and decoding program for use in quantum error correction

According to one embodiment, a mirror includes a plurality of dielectric layers stacked in a first direction. A thickness along the first direction of each of the dielectric layers is half a design wavelength. The dielectric layers include a first dielectric layer. The first dielectric layer includes a first portion with a thickness being &#x215b; of the design wavelength, a second portion stacked with the first portion with a thickness being &#x215b; of the design wavelength, and a third portion provided between the first and second portions with a thickness being &#xbc; of the design wavelength. The second portion has a refractive index lower than that of the first portion. The third portion has a refractive index gradually decreasing from a side of the first portion toward a side of the second portion.

Mirror

An operating method for stimulated Raman adiabatic passage to change probability amplitude in a three-level system including states of |0&#x3e;, |1&#x3e; and |e&#x3e;, 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&#x3e; and |e&#x3e; and between |1&#x3e; and |e&#x3e;, 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&#x3e; and energy of |e&#x3e;. 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&#x3e; and energy of |e&#x3e;.

Operating method for stimulated Raman adiabatic passage and operating method for phase gate

In an operation of two qubit gate having failure information related to success or failure, by using a code to concatenate N-error-correcting code transversally executing a Pauli gate, a Hadamard gate and a CNOT gate, an error-correction is executed by an error-correcting teleportation, and the CNOT gate is executed to an encoded qubit by the error-correcting teleportation. In Bell measurement of the error-correcting teleportation, when a measurement result of non-encoded qubit is processed, by suitably defining failure information of the encoded qubit of level (l+1) from the failure information of encoded qubits of level l, the measurement result of the encoded qubit of each level is determined, and the failure information of the encoded qubit of each level is defined. As a result, a measurement result of a logical qubit as the encoded qubit of the highest level is determined.

Quantum computing method and a quantum computer

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&#x3e;, |1&#x3e; and |3&#x3e;, the two energy states being represented by |2&#x3e; and |4&#x3e;, energies of |2&#x3e; and |4&#x3e; being higher than energies of |0&#x3e;, |1&#x3e; and |3&#x3e;, a transition frequency between |3&#x3e; and |2&#x3e; being equal to the resonance frequency, |0&#x3e; and |1&#x3e; 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.

Quantum computing method and quantum computer

An optical resonator includes a master resonator configured to resonate an electromagnetic wave, one structure or a pair of structures adjacent to each other, each of which is arranged at a position that overlaps one of resonance modes of the master resonator, is made up of a material in which a real part of a permittivity assumes a negative value, and an absolute value of the real part is larger than an absolute value of an imaginary part of the permittivity, and has a size which makes scattering that the electromagnetic wave suffers be Rayleigh scattering, and one or a plurality of particles, each of which is laid out near the structure by a distance smaller than the size of the structure.

Growing community of inventors

Yokohama, Japan

Kouichi Ichimura