Decryption device, quantum computer, decoding method, and program

Abstract

To realize a decryption device capable of operating even if there is a lattice shape deformation by lattice surgery.SOLUTION: A decryption device comprises multiple decryption processing parts for executing decrypting processing based on the observed value obtained from the quantum processor with multiple quantum bits configuring a logical quantum bit. Each decrypting processing part comprises a memory for storing the observed value of the multiple auxiliary bits obtained cyclically from the quantum processor as a two-dimensional array and identifies the data quantum bit in error by performing that each decrypting processing part searches the memory.SELECTED DRAWING: Figure 4

Claims

1. A decoding device that performs decoding based on observations obtained from a quantum processor having multiple qubits that constitute a logical qubit, Equipped with multiple decoding processing units, Each decoding unit includes a memory that stores the observed values ​​of a plurality of auxiliary qubits periodically acquired from the quantum processor as a two-dimensional array. Each decoding unit searches memory to identify the data qubit where the error occurred. Decoding device.

2. The aforementioned logical qubit contains multiple sequences consisting of multiple auxiliary qubits, each decoding unit corresponds to one sequence, and the two-dimensional position of the memory corresponds to the position of the auxiliary qubit in the sequence and the time position at which the observation value was acquired. The decoding device according to claim 1.

3. A specific decoding unit among the plurality of decoding units performs a search in its own memory, starting from a two-dimensional position with a predetermined value, and changing the two-dimensional position. If the two-dimensional position to be searched is outside the region of the logical qubit, it corrects the data qubit between the two-dimensional position with the predetermined value and the grid boundary of the logical qubit. The decoding device according to claim 1.

4. The system comprises a plurality of first decoding units corresponding to a first logical qubit and a plurality of second decoding units corresponding to a second logical qubit, and performs lattice surgery between the first logical qubit and the second logical qubit by copying the contents of the memory of each of the plurality of second decoding units to the memory of the corresponding first decoding unit in the plurality of first decoding units. The decoding device according to claim 1.

5. The system comprises a plurality of first decoding units corresponding to a first logical qubit and a plurality of second decoding units corresponding to a second logical qubit, and performs lattice surgery between the first logical qubit and the second logical qubit by connecting the plurality of first decoding units and the plurality of second decoding units. The decoding device according to claim 1.

6. A quantum computer comprising the decoding device according to any one of claims 1 to 5 and the quantum processor.

7. A decoding method performed by a decoding device that performs decoding based on observations obtained from a quantum processor having multiple qubits that constitute a logical qubit, The decoding device comprises a plurality of decoding processing units, Each decoding unit includes a memory that stores the observed values ​​of a plurality of auxiliary qubits periodically acquired from the quantum processor as a two-dimensional array. Each decoding unit searches memory to identify the data qubit where the error occurred. Decryption method.

8. A program for causing a computer to function as a decoding device according to any one of claims 1 to 5.

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