EP-4740143-A1 - QUANTUM COMPUTER

EP4740143A1EP 4740143 A1EP4740143 A1EP 4740143A1EP-4740143-A1

Abstract

Provided is a quantum computer, including: an input unit for inputting an electron wave packet; a propagation unit that propagates the electron wave packet in a predetermined direction and has a loop-like loop path; and a qubit generation unit that generates a time-bin qubit by using the electron wave packet.

Inventors

YAMAMOTO, Michihisa
TAKADA, Shintaro
BAUERLE, Christopher

Assignees

RIKEN
National Institute Of Advanced Industrial Science and Technology
Centre National de la Recherche Scientifique

Dates

Publication Date: 20260513
Application Date: 20230707

Claims (20)

A quantum computer, comprising: an input unit for inputting an electron wave packet; a propagation unit that propagates the electron wave packet in a predetermined direction and has a loop-like loop path; and a qubit generation unit that generates a time-bin qubit by using the electron wave packet.
The quantum computer according to claim 1, wherein the qubit generation unit includes: a first path that is provided on the loop path; a second path that branches off from the first path; and a common path that is connected to the first path and the second path for generating the time-bin qubit by using a first electron wave packet propagating from the first path and a second electron wave packet propagating from the second path.
The quantum computer according to claim 2, wherein a duration from a time when the first electron wave packet is input to the first path to a time when the first electron wave packet is input to the common path is shorter than a duration from a time when the second electron wave packet is input to the second path to a time when the second electron wave packet is input to the common path.
The quantum computer according to claim 3, wherein a propagation velocity of the first electron wave packet in the first path is higher than a propagation velocity of the second electron wave packet in the second path.
The quantum computer according to claim 3, wherein a length of the first path is shorter than a length of the second path.
The quantum computer according to claim 3, wherein a width of the first path is wider than a width of the second path.
The quantum computer according to claim 2, wherein the qubit generation unit has a switch gate that prevents an electron wave packet that is input from one of the first path and the second path to the common path from entering another of the first path and the second path.
The quantum computer according to claim 1, comprising a quantum operation unit for operating the time-bin qubit, wherein the quantum operation unit includes : a first operation path that is provided on the loop path and through which a first electron wave packet of the time-bin qubit propagates; a second operation path that branches off from the first operation path and through which the second electron wave packet of the time-bin qubit propagates; and an operation processing unit that controls a quantum state of at least one of the first electron wave packet and the second electron wave packet.
The quantum computer according to claim 8, wherein the quantum operation unit includes: a first delay path that is provided on the first operation path and delays the first electron wave packet and inputs it to the operation processing unit; and a second delay path that is provided on the second operation path and delays the second electron wave packet for which a quantum state is controlled by the operation processing unit.
The quantum computer according to claim 1, wherein the input unit includes an electron wave packet generation unit that generates the electron wave packet.
The quantum computer according to claim 1, comprising an output unit that extracts the time-bin qubit from the propagation unit.
The quantum computer according to claim 1, wherein the propagation unit includes a plurality of loop paths.
The quantum computer according to claim 12, comprising a quantum operation unit for operating the time-bin qubit, wherein the quantum operation unit includes a quantum entanglement state generation unit that generates a quantum entanglement state between a first time-bin qubit that propagates through a first loop path among the plurality of loop paths and a second time-bin qubit that propagates through a second loop path, which is different from the first loop path.
The quantum computer according to claim 1, comprising a propagation velocity adjustment unit that applies a gate voltage and adjusts a propagation velocity of the electron wave packet.
The quantum computer according to claim 14, wherein the propagation velocity adjustment unit includes: a first voltage application unit that is provided on the loop path; and a second voltage application unit that is provided at a predetermined distance from the first voltage application unit in the loop path.
The quantum computer according to claim 1, wherein the input unit inputs a plurality of electron wave packets, the qubit generation unit generates a plurality of time-bin qubits by using the plurality of electron wave packets, and the propagation unit propagates the plurality of time-bin qubits.
The quantum computer according to claim 16, comprising a quantum operation unit for operating the plurality of time-bin qubits, wherein the quantum operation unit includes an operation processing unit that controls a quantum state between a which-path qubit into which a first time-bin qubit among the plurality of time-bin qubits is converted and a which-path qubit into which a second time-bin qubit, which is different from the first time-bin qubit, is converted.
The quantum computer according to claim 16, comprising a comparison unit that compares quantum states of at least two time-bin qubits among the plurality of time-bin qubits.
The quantum computer according to claim 18, wherein the comparison unit converts the at least two time-bin qubits into at least two which-path qubits, and compares quantum states of the at least two which-path qubits.
The quantum computer according to claim 18, comprising a quantum operation unit for operating the plurality of time-bin qubits, wherein the quantum operation unit includes a modulation unit that modulates an operation of a quantum state of the plurality of time-bin qubits depending on a comparison result of the comparison unit.

Description

QUANTUM COMPUTER The present invention relates to a quantum computer. Non-Patent Document 1 describes 'fling qubit' architectures-systems. Citation List Non-Patent Literature 　　Non-Patent Document 1: Michihisa Yamamoto, et. al., "Electrical control of a solid-state flying qubit," NATURE NANOTECHNOLOGY, 18 March, 2012, Vol. 7, p. 247-251 　　Non-Patent Document 2: Hermann Edlbauer, et. al., "Semiconductor-based electron flying qubits: review on recent progress accelerated by numerical modeling," EPJ Quantum Technology, 10 August, 2022, Vol.9, 21 In an aspect of the present invention, a quantum computer is provided, which includes an input unit for inputting an electron wave packet; a propagation unit that propagates the electron wave packet in a predetermined direction and has a loop-like loop path; and a qubit generation unit that generates a time-bin qubit by using the electron wave packet. In the quantum computer described above, the qubit generation unit may have a first path provided on the loop path. The qubit generation unit may have a second path that branches off from the first path. The qubit generation unit may include a common path that is connected to the first path and the second path, for generating the time-bin qubit using a first electron wave packet propagating from the first path and a second electron wave packet propagating from the second path. In any quantum computer described above, a duration from a time when the first electron wave packet is input to the first path to a time when it is input to the common path may be shorter than a duration from a time when the second electron wave packet is input to the second path to a time when it is input to the common path. In any quantum computer described above, the propagation velocity of the first electron wave packet in the first path may be higher than the propagation velocity of the second electron wave packet in the second path. In any quantum computer described above, the length of the first path may be shorter than the length of the second path. In any quantum computer described above, the width of the first path may be wider than the width of the second path. In any quantum computer described above, the qubit generation unit may include a switch gate that prevents an electron wave packet that is input from one of the first path and the second path to the common path from entering the other of the first path and the second path. Any quantum computer described above may include a quantum operation unit for operating the time-bin qubit. The quantum operation unit may include a first operation path that is provided on the loop path and through which the first electron wave packet of the time-bin qubit is propagated; a second operation path that branches off from the first operation path and through which the second electron wave packet of the time-bin qubit is propagated; and an operation processing unit that controls a quantum state of at least one of the first electron wave packet and the second electron wave packet. In any quantum computer described above, the quantum operation unit may include: a first delay path that is provided on the first operation path and delays the first electron wave packet and inputs it to the operation processing unit; and a second delay path that is provided on the second operation path and delays the second electron wave packet for which a quantum state is controlled by the operation processing unit. In any quantum computer described above, the input unit may have an electron wave packet generation unit that generates the electron wave packet. Any quantum computer described above may include an output unit that extracts the time-bin qubit from the propagation unit. In any quantum computer described above, the propagation unit may have a plurality of loop paths. Any quantum computer described above may include a quantum operation unit for operating the time-bin qubit. The quantum operation unit may include a quantum entanglement state generation unit that generates a quantum entanglement state between a first time-bin qubit that propagates through the first loop path among the plurality of loop paths and a second time-bin qubit that propagates through a second loop path, which is different from the first loop path. Any quantum computer described above may include a propagation velocity adjustment unit that applies a negative gate voltage and adjusts the propagation velocity of the electron wave packet. In any quantum computer described above, the propagation velocity adjustment unit may include a first voltage application unit provided on the loop path; and a second voltage application unit provided at a predetermine distance from the first voltage application unit in the loop path. In any quantum computer described above, the input unit may input a plurality of electron wave packets. The qubit generation unit may generate the plurality of time-bin qubits by using the plurality of electron wave packets.