# US 2025/0165221 A1 · Quantum control system architecture for real-time pauli twirling of quantum programs

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- Number: US 2025/0165221 A1
- Document ID: US20250165221A1
- Status: Published application
- Kind: A1
- Application number: 18/514,200
- Filed: 2023-11-20
- Published: 2025-05-22
- Earliest claimed: 2023-11-20
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Thomas Alexander; Ian Hincks; Michael B. Healy; Scott M. Willenborg
- Web page: https://patentgrep.com/patent/US20250165221A1

## CPC

- G06F 7/582: {Pseudo-random number generators}
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Systems, computer program products and/or computer-implemented methods described herein relate to a quantum control system architecture for real-time Pauli twirling of quantum programs. A system can include a memory that stores computer executable components and a processor that executes the computer executable components, which can include an initialization component that determines a seed to be applied to a first pseudorandom number generator (PRNG) associated with a first qubit of an input quantum circuit, the seed being shared with one or more second PRNGs associated with respective second qubits of the input quantum circuit that share a frame with the first qubit; and a Pauli twirling component that applies selected Clifford operations to the first qubit before and after execution of respective layers of the input quantum circuit, where the selected Clifford operations are selected according to an output of the first PRNG that is produced based on the seed.

## Claims

### Claim 1

A system, comprising:
a memory that stores computer executable components; and
a processor that executes the computer executable components stored in the memory, wherein the computer executable components comprise:
an initialization component that determines a seed to be applied to a first pseudorandom number generator (PRNG) associated with a first qubit of an input quantum circuit, the seed being shared with one or more second PRNGs associated with respective second qubits of the input quantum circuit that share a frame with the first qubit; and
a Pauli twirling component that applies selected Clifford operations to the first qubit before and after execution of respective layers of the input quantum circuit, resulting in a twirled quantum circuit, wherein the selected Clifford operations are selected according to an output of the first PRNG that is produced based on the seed.

### Claim 2 (depends on 1)

The system of claim 1, wherein the initialization component receives the seed in a control message from a control system prior to execution of the input quantum circuit, and wherein the control message causes the system to execute the input quantum circuit at an action time specified by the control message.

### Claim 3 (depends on 1)

The system of claim 1, wherein the selected Clifford operations are selected from the group consisting of an identity gate, a Pauli-X gate, a Pauli-Y gate, and a Pauli-Z gate.

### Claim 4 (depends on 1)

The system of claim 1, wherein the computer executable components further comprise:
a sampling component that samples values from the first PRNG; and
a lookup component that selects the selected Clifford operations based on a defined mapping between the values and the selected Clifford operations.

### Claim 5 (depends on 1)

The system of claim 1, wherein the computer executable components further comprise:
a phase update component that modifies, at the respective layers of the input quantum circuit, a phase of the frame of the first qubit according to a function of the selected Clifford operations.

### Claim 6 (depends on 5)

The system of claim 5, wherein the computer executable components further comprise:
a decomposition component that defines a rotation of the first qubit via a series of quantum gates, wherein the phase update component modifies the phase of the frame of the first qubit by applying a phase rotation to at least one gate of the series of quantum gates.

### Claim 7 (depends on 6)

The system of claim 6, wherein an amount of the phase rotation is defined by an instruction provided to the system by a control system.

### Claim 8 (depends on 1)

The system of claim 1, wherein:
the selected Clifford operations are first selected Clifford operations,
the Pauli twirling component applies the first selected Clifford operations to the first qubit before and after execution of the respective layers of a first instance of the input quantum circuit, resulting in a first twirled quantum circuit,
the output of the first PRNG is a first output, and
the Pauli twirling component further applies second selected Clifford operations to the first qubit before and after execution of the respective layers of a second instance of the input quantum circuit, resulting in a second twirled quantum circuit, the second selected Clifford operations being selected according to a second output of the first PRNG that is produced based on the seed and without reloading the input quantum circuit.

### Claim 9 (depends on 1)

The system of claim 1, wherein the initialization component derives the seed from a first clock signal associated with the first PRNG, the first clock signal being synchronized with a second clock signal associated with the one or more second PRNGs.

### Claim 10

A computer-implemented method, comprising:
determining, by a system operatively coupled to a processor, a seed to be applied to a first pseudorandom number generator (PRNG) associated with a first qubit of an input quantum circuit, the seed being shared with one or more second PRNGs associated with respective second qubits of the input quantum circuit that share a frame with the first qubit; and
applying, by the system, selected Clifford operations to the first qubit before and after execution of respective layers of the input quantum circuit, resulting in a twirled quantum circuit, wherein the selected Clifford operations are selected according to an output of the first PRNG that is produced based on the seed.

### Claim 11 (depends on 10)

The computer-implemented method of claim 10, wherein the determining of the seed further comprises receiving the seed in a control message from a control system prior to execution of the input quantum circuit, and wherein the computer-implemented method further comprises:
executing, by the system, the input quantum circuit at an action time specified by the control message.

### Claim 12 (depends on 10)

The computer-implemented method of claim 10, wherein the selected Clifford operations are selected from the group consisting of an identity gate, a Pauli-X gate, a Pauli-Y gate, and a Pauli-Z gate.

### Claim 13 (depends on 10)

The computer-implemented method of claim 10, further comprising:
sampling, by the system, values from the first PRNG; and
selecting, by the system, the selected Clifford operations based on a defined mapping between the values and the selected Clifford operations.

### Claim 14 (depends on 10)

The computer-implemented method of claim 10, further comprising:
modifying, by the system and at the respective layers of the input quantum circuit, a phase of the frame of the first qubit according to a function of the selected Clifford operations.

### Claim 15 (depends on 10)

The computer-implemented method of claim 10, wherein the selected Clifford operations are first selected Clifford operations, wherein the applying comprises applying the first selected Clifford operations to the first qubit before and after execution of the respective layers of a first instance of the input quantum circuit, resulting in a first twirled quantum circuit, wherein the output of the first PRNG is a first output, and wherein the computer-implemented method further comprises:
applying, by the system, second selected Clifford operations to the first qubit before and after execution of the respective layers of a second instance of the input quantum circuit, resulting in a second twirled quantum circuit, the second selected Clifford operations being selected according to a second output of the first PRNG that is produced based on the seed and without reloading the input quantum circuit.

### Claim 16

A computer program product facilitating a process to facilitate real-time Pauli twirling of quantum programs with control flow, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
determine, by the processor, a seed to be applied to a first pseudorandom number generator (PRNG) associated with a first qubit of an input quantum circuit, the seed being shared with one or more second PRNGs associated with respective second qubits of the input quantum circuit that share a frame with the first qubit; and
apply, by the processor, selected Clifford operations to the first qubit before and after execution of respective layers of the input quantum circuit, wherein the selected Clifford operations are selected according to an output of the first PRNG that is produced based on the seed.

### Claim 17 (depends on 16)

The computer program product of claim 16, wherein the program instructions are further executable by the processor to cause the processor to:
receive, by the processor, the seed in a control message from a control system prior to execution of the input quantum circuit; and
execute, by the processor, the input quantum circuit at an action time specified by the control message.

### Claim 18 (depends on 16)

The computer program product of claim 16, wherein the selected Clifford operations are selected from the group consisting of an identity gate, a Pauli-X gate, a Pauli-Y gate, and a Pauli-Z gate.

### Claim 19 (depends on 16)

The computer program product of claim 16, wherein the program instructions are further executable by the processor to cause the processor to:
sample, by the processor, values from the first PRNG; and
select, by the processor, the selected Clifford operations based on a defined mapping between the values and the selected Clifford operations.

### Claim 20 (depends on 16)

The computer program product of claim 16, wherein the program instructions are further executable by the processor to cause the processor to:
modify, at the respective layers of the input quantum circuit, a phase of the frame of the first qubit according to a function of the selected Clifford operations.