Method and program for changing resource state of quantum computer

Abstract

No method has been proposed to convert a computationally universal resource state into a quantum universal resource state, and thus it has been necessary to construct the respective resource states individually. According to a method of the present disclosure, a computationally universal resource state, once constructed, can be used to newly construct a quantum universal resource state. Also, the method of the present disclosure is applicable to any computationally universal resource state allowing for the execution of H and CCZ gates, and thus also has the versatility of also being applicable to as-yet undiscovered computationally universal resource states.

Description

Method and Program for Modifying Resource State of Quantum Computer

[0001] The present disclosure relates to a quantum computer, and specifically to a method for converting a quantum computer with limited functionality into a full-spec quantum computer.

[0002]

[0003]

[0004]

[0005]

[0006]

[0007] Conventionally, a computationally universal resource state and a quantum state universal resource state have been configured individually, and no method for converting them has been devised. In the present disclosure, a method for converting a computationally universal resource state into a quantum state universal resource state without changing the necessary measurement basis is proposed.

[0008] The present disclosure proposes a method for converting a computationally universal resource state into a quantum state universal resource state. Specifically, as one embodiment, a method for converting a computationally universal resource state of a quantum computer equipped only with Hadamard gates and Toffoli (CCZ) gates into a quantum state universal resource state, characterized in that a quantum state conversion unit in the quantum computer converts a part of the computationally universal resource state into qubits in the +1 eigenstate of Pauli Y, and a quantum state storage unit in the quantum computer stores the resource state converted in the quantum state conversion unit.

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

[0015] Furthermore, resource states including qubits converted using the quantum state conversion unit 405 can be stored in the quantum state storage unit 407. The resource states stored in the quantum state storage unit 407 are used in calculations by calling the necessary quantum states from the actual calculation unit 409 according to the calculation process. Here, the actual calculation unit 409 has the function of performing actual quantum calculations and may include, for example, quantum circuits 30 and 40 equipped with various gates as shown in Figures 2 and 3. Moreover, the quantum state conversion unit 405, the quantum state storage unit 407, and the actual calculation unit 409 are provided within the quantum computer 400 and are connected to each other.

[0016]

[0017] Referring to Figures 2 and 3, the operation of a measurement-type quantum computation using a quantum state-universal resource state obtained by the transformation method of this disclosure will be explained. Figure 2 is a diagram showing steps 1 and 2 described later, and shows a quantum circuit 30 composed of an H gate and a CCZ gate. Here, the CCZ gate is represented as a vertical line as a unitary matrix for 3 qubits. The CZ gate can also be composed of a combination of an H gate and a CCZ gate, as shown by the dotted box in Figure 2. The quantum circuit 30 is executed from left to right.

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] Also, the unitary operation in the quantum circuit 40 can be divided into a first half portion 301 and a second half portion 302. The second half portion 302 of the quantum circuit 40 can be calculated and handled for the second and third qubits as in the following equation 3.

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036] Figure 4 shows a system for setting up a quantum computer to perform the method of transforming resource states of the present disclosure. The system has a control computer 410 connected to a quantum computer 400. The method of the present disclosure can be performed by executing a program 419 by the control computer 410 connected to the quantum computer 400. The quantum computer 400 comprises a plurality of H gates 401 and a plurality of CCZ gates 403 and performs quantum computations on various resource states. The control computer 410 is connected to the quantum computer 400 and includes, for example, one or more CPUs 411, memory 413, input / output controllers 415, and storage 417 that can store the program 419. The program 419 stored in the control computer 410 can send instructions to the quantum computer 400 to perform the method of the present disclosure. The storage 417 is a non-temporary computer-readable medium which may consist of one or more of a hard disk, CD, DVD, or SSD and provides a region for storing the program 419. The memory 413 may consist of RAM, ROM, and EEPROM. The program 419 may be stored in the ROM and EEPROM that make up the memory 413.

[0037] As can be seen in the steps above, the transformation method of this disclosure uses only H and CCZ gates, so the set of required measurement bases does not change before and after the transformation, and has the advantage of being applicable to any computationally universal resource state in which H and CCZ gates can be executed.

[0038] Until now, no method had been proposed for converting computationally universal resource states into quantum state-universal ones. Therefore, it was necessary to construct each resource state individually. This disclosure makes it possible to construct new quantum state-universal resource states using computationally universal resource states, provided that computationally universal resource states can be constructed. Furthermore, because the method is applicable to any computationally universal resource state, it also has the versatility to be applied to computationally universal resource states that have not yet been discovered.

[0039] 10 Computational universal resource state 20 Quantum state universal resource state 30, 40 Quantum circuit 101 Input qubit 103 Output qubit 105 Pauli Y eigenstate 201, 202, 203 CZ gate 301 First half of quantum circuit 302 Second half of quantum circuit (SWAP gate) 400 Quantum computer 401 H gate 403 CCZ gate 405 Quantum state conversion unit 407 Quantum state storage unit 409 Actual calculation unit 410 Control computer 411 CPU 413 Memory 415 I / O controller 417 Storage 419 Program

Claims

1. A method for converting a computationally universal resource state of a quantum computer equipped only with Hadamard gates and controlled-controlled Z (CCZ) gates into a quantum state-universal resource state, comprising the steps of: a quantum state conversion unit in the quantum computer converting a portion of the computationally universal resource state into a qubit of the +1 eigenstate of Pauli Y; and a quantum state storage unit in the quantum computer storing the resource state converted in the quantum state conversion unit.

2.

3. The method according to claim 1, wherein the Hadamard gate is subjected to an operation to create a superposition state, and the CCZ gate is subjected to an operation to create an entangled state.

4. A program that causes a computer equipped with a processor, connected to the quantum computer, to execute the method according to claim 1.

Images