Kabushiki Kaisha Toshiba

Mamiko Kujiraoka

Satoshi Nakamura

Hayato Goto

Kouichi Ichimura

Yoshimichi Tanizawa

Ririka Takahashi

Kazuaki Doi

Akira Murakami

Hironori Uchikawa

Hideaki Sato

According to an embodiment, a quantum cryptographic device includes a memory and one or more processors coupled to the memory. The one or more processors are configured to: tabulate information on an application key transmitted and received by using a quantum cryptographic key and output an application-key information tabulation result; calculate a unit price of the application key based on the application-key information tabulation result; and display information that is display information including the unit price of the application key.

Quantum cryptographic device, quantum cryptographic communication fee calculation system, and quantum cryptographic communication fee calculation method

According to an embodiment, an application-key management system includes a plurality of application-key management devices and a comprehensive management device. The application-key management devices each include: a first memory configured to store an application key in one or more separated logical drives for each sharing destination of the application key shared by quantum cryptographic communication; and a first processor coupled to the first memory. The first processor is configured to: receive, from the comprehensive management device, a deletion request of specifying a logical drive storing the application key to be deleted among the logical drives; and delete the application key stored in the logical drive specified by the deletion request.

Application-key management system, application-key management device, application-key management method, and computer program product

According to an embodiment, an information processor includes a memory and one or more hardware processors coupled to the memory. The one or more hardware processors are configured to function as a calculating unit, a determining unit, and a generating unit. The calculating unit is configured to calculate a key length. The determining unit is configured to determine a block size corresponding to a unit of processing in key generation and an outputtable size indicating the size of a key outputtable by the key generation. The generating unit is configured to generate a key having the key length by a hash operation using a matrix having a size determined by the block size and the outputtable size.

Key generation device, key generation method, and computer program product

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 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.

Growing community of inventors

Kawasaki, Japan

Mamiko Kujiraoka