# US 2020/0401927 A1 · Methods and devices for obtaining quantum cluster states with high fault tolerance

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- Number: US 2020/0401927 A1
- Document ID: US20200401927A1
- Status: Published application
- Kind: A1
- Application number: 17/013,192
- Filed: 2020-09-04
- Published: 2020-12-24
- Earliest claimed: 2018-03-07
- Assignees: Psiquantum, Corp.
- Applicants: Psiquantum Corp.
- Inventors: Naomi NICKERSON; Terence RUDOLPH
- Web page: https://patentgrep.com/patent/US20200401927A1

## CPC

- G06N 10/40: Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control
- G06F 13/36: for access to common bus or bus system
- G06F 13/40: Bus structure {(for computer networks G06F15/163; for optical bus networks H04B10/25)}
- G06F 15/16: Combinations of two or more digital computers each having at least an arithmetic unit, a program unit and a register, e.g. for a simultaneous processing of several programs {(coordinating program control therefor G06F9/52; in regulating and control system G05B)}
- G06N 10/00: Quantum computing, i.e. information processing based on quantum-mechanical phenomena
- G06N 10/70: Quantum error correction, detection or prevention, e.g. surface codes or magic state distillation
- G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A method for obtaining a plurality of entangled qubits represented by a lattice structure that includes a plurality of contiguous lattice cells. A respective edge of a respective lattice cell corresponds to one or more edge qubits, and a respective face of the respective lattice cell corresponding to one or more face qubits. Each face qubit is entangled with adjacent edge qubits. A first face of the respective lattice cell corresponds to two or more face qubits, and/or a first edge corresponds to two or more edge qubits. A device for obtaining the plurality of entangled qubits represented by the above-described lattice structure is also described.

## Claims

### Claim 1

A method, comprising:
obtaining a plurality of entangled qubits represented by a lattice structure, the lattice structure including a plurality of contiguous lattice cells, a respective edge of a respective lattice cell corresponding to one or more qubits of the plurality of entangled qubits, a respective face of the respective lattice cell corresponding to one or more qubits of the plurality of entangled qubits, each qubit of the one or more qubits that correspond to the respective face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the respective face of the respective lattice cell, wherein at least one of the following is satisfied:
at least a first face of the respective lattice cell corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the first face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the first face of the respective lattice cell, and
at least a first edge of the respective lattice cell corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the first edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the first edge of the respective lattice cell.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the first face of the respective lattice cell corresponds to two or more qubits, of the plurality of entangled qubits, including a first qubit and a second qubit that is distinct from the first qubit; and
the first qubit is not directly entangled with the second qubit.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
the first face is a rectangular face defined by four edges of the respective lattice cell.

### Claim 4 (depends on 1)

The method of claim 1, wherein:
the first face is a triangular face defined by three edges of the respective lattice cell.

### Claim 5 (depends on 1)

The method of claim 1, wherein:
a second face of the respective lattice cell, that is distinct from the first face of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the second face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the second face of the respective lattice cell.

### Claim 6 (depends on 5)

The method of claim 5, wherein:
the second face is a rectangular face defined by four edges of the respective lattice cell.

### Claim 7 (depends on 5)

The method of claim 5, wherein:
the second face is a triangular face defined by three edges of the respective lattice cell.

### Claim 8 (depends on 5)

The method of claim 5, wherein:
a third face of the respective lattice cell, that is distinct from the first face and the second face of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the third face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the third face of the respective lattice cell.

### Claim 9 (depends on 8)

The method of claim 8, wherein:
the third face is a rectangular face defined by four edges of the respective lattice cell.

### Claim 10 (depends on 8)

The method of claim 8, wherein:
the third face is a triangular face defined by three edges of the respective lattice cell.

### Claim 11 (depends on 8)

The method of claim 8, wherein:
a fourth face of the respective lattice cell, that is distinct from the first face, the second face, and the third face of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the fourth face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the fourth face of the respective lattice cell.

### Claim 12 (depends on 11)

The method of claim 11, wherein:
the fourth face is a rectangular face defined by four edges of the respective lattice cell.

### Claim 13 (depends on 11)

The method of claim 11, wherein:
the fourth face is a triangular face defined by three edges of the respective lattice cell.

### Claim 14 (depends on 11)

The method of claim 11, wherein:
a fifth face of the respective lattice cell, that is distinct from the first face, the second face, the third face, and the fourth face of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the fifth face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the fifth face of the respective lattice cell.

### Claim 15 (depends on 14)

The method of claim 14, wherein:
the fifth face is a rectangular face defined by four edges of the respective lattice cell.

### Claim 16 (depends on 14)

The method of claim 14, wherein:
a sixth face of the respective lattice cell, that is distinct from the first face, the second face, the third face, the fourth face, and the fifth face of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the sixth face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the sixth face of the respective lattice cell.

### Claim 17 (depends on 1)

The method of claim 1, wherein:
the first edge of the respective lattice cell corresponds to two or more qubits, of the plurality of entangled qubits, including a third qubit and a fourth qubit that is distinct from the third qubit; and
the third qubit is not directly entangled with the fourth qubit.

### Claim 18 (depends on 17)

The method of claim 17, wherein:
a second edge of the respective lattice cell, that is distinct from the first edge of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the second edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the second edge of the respective lattice cell.

### Claim 19 (depends on 18)

The method of claim 18, wherein:
a third edge of the respective lattice cell, that is distinct from the first edge and the second edge of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the third edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the third edge of the respective lattice cell.

### Claim 20 (depends on 19)

The method of claim 19, wherein:
a fourth edge of the respective lattice cell, that is distinct from the first edge, the second edge, and the third edge of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the fourth edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the fourth edge of the respective lattice cell.

### Claim 21 (depends on 20)

The method of claim 20, wherein:
a fifth edge of the respective lattice cell, that is distinct from the first edge, the second edge, the third edge, and the fourth edge of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the fifth edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the fifth edge of the respective lattice cell.

### Claim 22 (depends on 21)

The method of claim 21, wherein:
a sixth edge of the respective lattice cell, that is distinct from the first edge, the second edge, the third edge, the fourth edge, and the fifth edge of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the sixth edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the sixth edge of the respective lattice cell.

### Claim 23 (depends on 22)

The method of claim 22, wherein:
a seventh edge of the respective lattice cell, that is distinct from the first edge, the second edge, the third edge, the fourth edge, the fifth edge, and the sixth edge of the respective lattice cell, corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the seventh edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the seventh edge of the respective lattice cell.

### Claim 24 (depends on 1)

The method of claim 1, wherein:
obtaining the plurality of entangled qubits includes fusing (i) at least one qubit of a first set of multiple entangled qubits and (ii) at least one qubit of a second set of multiple entangled qubits, the second set of multiple entangled qubits being mutually exclusive from the first set of multiple entangled qubits.

### Claim 25 (depends on 24)

The method of claim 24, wherein:
the first set of multiple entangled qubits includes three or more qubits; and
the second set of multiple entangled qubits includes two or more qubits.

### Claim 26 (depends on 1)

The method of claim 1, wherein:
obtaining the plurality of entangled qubits includes:
receiving a first set of entangled qubits, including a first center qubit entangled with three or more peripheral qubits;
receiving a second set of entangled qubits, including a second center qubits entangled with three or more peripheral qubits, the second set of entangled qubits being mutually exclusive to the first set of entangled qubits; and
fusing each peripheral qubit of the first set of entangled qubits with a respective peripheral qubit of the second set of entangled qubits.

### Claim 27

A method, comprising:
obtaining a first set of multiple entangled qubits;
obtaining a second set of multiple entangled qubits, the second set of multiple entangled qubits being mutually exclusive from the first set of multiple entangled qubits; and
fusing (i) at least one qubit of the first set of multiple entangled qubits and (ii) at least one qubit of the second set of multiple entangled qubits, thereby obtaining a plurality of entangled qubits represented by a lattice structure, the lattice structure including a plurality of contiguous lattice cells, a respective edge of a respective lattice cell corresponding to one or more qubits of the plurality of entangled qubits, a respective face of the respective lattice cell corresponding to one or more qubits of the plurality of entangled qubits, each qubit of the one or more qubits that correspond to the respective face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the respective face of the respective lattice cell, wherein:
at least one of the following is satisfied:
at least a first face of the respective lattice cell corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the first face of the respective lattice cell being entangled with respective qubits that correspond to respective edges of the respective lattice cell that are adjacent to the first face of the respective lattice cell, and
at least a first edge of the respective lattice cell corresponds to two or more qubits of the plurality of entangled qubits, each qubit of the two or more qubits that correspond to the first edge of the respective lattice cell being entangled with respective qubits that correspond to respective faces of the respective lattice cell that are adjacent to the first edge of the respective lattice cell.