US-20260127466-A1 - OPTIMIZING CLASSICAL RESOURCES DURING TRANSPILATION OF DYNAMIC QUANTUM CIRCUITS

Abstract

A method, system, and computer program product for improving transpilation of dynamic quantum circuits. Classical resources utilized by the dynamic quantum circuit are optimized during transpilation of the dynamic quantum circuit so as to reduce the classical resource requirements. Such optimization of the classical resources is based on optimizing the classical memory requirements, optimizing the classical processing time, and/or optimizing the classical information flow. Upon optimizing, during transpilation, the classical resources utilized by the dynamic quantum circuit, a set of classical instructions is generated based on the optimization of the classical resources. Such classical instructions are then compiled during the transpilation of the dynamic quantum circuit. As a result, there is an improved performance of the transpiled dynamic quantum circuit, including an improvement in the quantum computational performance.

Inventors

• Derek Wang
• Pedro Rivero Ramirez
• Iskandar Sitdikov
• Alireza Seif Tabrizi
• Haimeng ZHANG

Assignees

• INTERNATIONAL BUSINESS MACHINES CORPORATION

Dates

Publication Date

20260507

Application Date

20241017

Claims (20)

1. 1 . A method for improving transpilation of dynamic quantum circuits, the method comprising: optimizing, during transpilation of a dynamic quantum circuit, classical resources utilized by said dynamic quantum circuit to reduce classical resource requirements; generating a set of classical instructions based on said optimization of said classical resources utilized by said dynamic quantum circuit; and compiling said set of classical instructions during said transpilation of said dynamic quantum circuit.
2. 2 . The method as recited in claim 1 further comprising: optimizing said classical resources utilized by said dynamic quantum circuit by performing one or more of the following in the group consisting of: optimizing classical memory requirements, optimizing classical processing time, and optimizing classical information flow.
3. 3 . The method as recited in claim 2 , wherein said classical memory requirements are optimized by performing one or more of the following in the group consisting of: re-using a classical register for a repeat-until-success loop, merging classical bits in response to identifying symmetries in classical logic conditions, minimizing classical bit requirements over segments of said dynamic quantum circuit, and re-using said classical register based on scheduling of parallel operations in said dynamic quantum circuit.
4. 4 . The method as recited in claim 2 , wherein said classical processing time is optimized by minimizing feed-forward times.
5. 5 . The method as recited in claim 2 , wherein said classical processing time is optimized by performing one or more of the following in the group consisting of: identifying a shortest feed-forward time for a classical expression out of a plurality of classical expressions, approximating compilation, optimizing quantum gates across classical logic conditions, projecting out a parity measurement to an ancilla qubit, and storing a single bit in response to unitaries being determined by a symmetry of a wave function.
6. 6 . The method as recited in claim 2 , wherein said classical information flow is optimized by performing one or more of the following in the group consisting of: limiting a classical processor to not store greater than a maximum number of bits per time step in order to prevent crashing, identifying classical logic conditions to be performed in sequence versus parallel in order to optimize classical logic with cumulative cost functions, and identifying quantum gates that can be performed in parallel with classical logic.
7. 7 . The method as recited in claim 1 , wherein said set of classical instructions is compiled between an optimization step and a scheduling step during said transpilation of said dynamic quantum circuit.
8. 8 . A computer program product for improving transpilation of dynamic quantum circuits, the computer program product comprising one or more computer readable storage mediums having program code embodied therewith, the program code comprising programming instructions for: optimizing, during transpilation of a dynamic quantum circuit, classical resources utilized by said dynamic quantum circuit to reduce classical resource requirements; generating a set of classical instructions based on said optimization of said classical resources utilized by said dynamic quantum circuit; and compiling said set of classical instructions during said transpilation of said dynamic quantum circuit.
9. 9 . The computer program product as recited in claim 8 , wherein the program code further comprises the programming instructions for: optimizing said classical resources utilized by said dynamic quantum circuit by performing one or more of the following in the group consisting of: optimizing classical memory requirements, optimizing classical processing time, and optimizing classical information flow.
10. 10 . The computer program product as recited in claim 9 , wherein said classical memory requirements are optimized by performing one or more of the following in the group consisting of: re-using a classical register for a repeat-until-success loop, merging classical bits in response to identifying symmetries in classical logic conditions, minimizing classical bit requirements over segments of said dynamic quantum circuit, and re-using said classical register based on scheduling of parallel operations in said dynamic quantum circuit.
11. 11 . The computer program product as recited in claim 9 , wherein said classical processing time is optimized by minimizing feed-forward times.
12. 12 . The computer program product as recited in claim 9 , wherein said classical processing time is optimized by performing one or more of the following in the group consisting of: identifying a shortest feed-forward time for a classical expression out of a plurality of classical expressions, approximating compilation, optimizing quantum gates across classical logic conditions, projecting out a parity measurement to an ancilla qubit, and storing a single bit in response to unitaries being determined by a symmetry of a wave function.
13. 13 . The computer program product as recited in claim 9 , wherein said classical information flow is optimized by performing one or more of the following in the group consisting of: limiting a classical processor to not store greater than a maximum number of bits per time step in order to prevent crashing, identifying classical logic conditions to be performed in sequence versus parallel in order to optimize classical logic with cumulative cost functions, and identifying quantum gates that can be performed in parallel with classical logic.
14. 14 . The computer program product as recited in claim 8 , wherein said set of classical instructions is compiled between an optimization step and a scheduling step during said transpilation of said dynamic quantum circuit.
15. 15 . A system, comprising: a memory for storing a computer program for improving transpilation of dynamic quantum circuits; and a processor connected to said memory, wherein said processor is configured to execute program instructions of the computer program comprising: optimizing, during transpilation of a dynamic quantum circuit, classical resources utilized by said dynamic quantum circuit to reduce classical resource requirements; generating a set of classical instructions based on said optimization of said classical resources utilized by said dynamic quantum circuit; and compiling said set of classical instructions during said transpilation of said dynamic quantum circuit.
16. 16 . The system as recited in claim 15 , wherein the program instructions of the computer program further comprise: optimizing said classical resources utilized by said dynamic quantum circuit by performing one or more of the following in the group consisting of: optimizing classical memory requirements, optimizing classical processing time, and optimizing classical information flow.
17. 17 . The system as recited in claim 16 , wherein said classical memory requirements are optimized by performing one or more of the following in the group consisting of: re-using a classical register for a repeat-until-success loop, merging classical bits in response to identifying symmetries in classical logic conditions, minimizing classical bit requirements over segments of said dynamic quantum circuit, and re-using said classical register based on scheduling of parallel operations in said dynamic quantum circuit.
18. 18 . The system as recited in claim 16 , wherein said classical processing time is optimized by minimizing feed-forward times.
19. 19 . The system as recited in claim 16 , wherein said classical processing time is optimized by performing one or more of the following in the group consisting of: identifying a shortest feed-forward time for a classical expression out of a plurality of classical expressions, approximating compilation, optimizing quantum gates across classical logic conditions, projecting out a parity measurement to an ancilla qubit, and storing a single bit in response to unitaries being determined by a symmetry of a wave function.
20. 20 . The system as recited in claim 16 , wherein said classical information flow is optimized by performing one or more of the following in the group consisting of: limiting a classical processor to not store greater than a maximum number of bits per time step in order to prevent crashing, identifying classical logic conditions to be performed in sequence versus parallel in order to optimize classical logic with cumulative cost functions, and identifying quantum gates that can be performed in parallel with classical logic.

Description

TECHNICAL FIELD The present disclosure relates generally to transpilation of dynamic quantum circuits, and more particularly to optimizing classical resources during transpilation of dynamic quantum circuits so as to improve the quantum computational performance. BACKGROUND Dynamic quantum circuits are quantum circuits with mid-circuit measurements and feed-forward classical operations which allow such circuits to be adaptive on-the-fly. A mid-circuit measurement is a quantum measurement at an intermediate point in the quantum circuit as opposed to a measurement at the end point of the quantum circuit thereby allowing dynamic adaptations based on the results. Feed-forward classical operations (or simply referred to herein as “feed-forward operations”) refer to the real-time adaptation of the quantum circuits based on earlier measurement outcomes. SUMMARY In one embodiment of the present disclosure, a method for improving transpilation of dynamic quantum circuits comprises optimizing, during transpilation of a dynamic quantum circuit, classical resources utilized by the dynamic quantum circuit to reduce classical resource requirements. The method further comprises generating a set of classical instructions based on the optimization of the classical resources utilized by the dynamic quantum circuit. The method additionally comprises compiling the set of classical instructions during the transpilation of the dynamic quantum circuit. Other forms of the embodiment of the method described above are in a system and in a computer program product. The foregoing has outlined rather generally the features and technical advantages of one or more embodiments of the present disclosure in order that the detailed description of the present disclosure that follows may be better understood. Additional features and advantages of the present disclosure will be described hereinafter which may form the subject of the claims of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present disclosure can be obtained when the following detailed description is considered in conjunction with the following drawings, in which: FIG. 1 illustrates a communication system for practicing the principles of the present disclosure in accordance with an embodiment of the present disclosure; FIG. 2 is a diagram of the software components of the classical computer for improving the transpilation of the dynamic quantum circuits so as to improve the quantum computational performance in accordance with an embodiment of the present disclosure; FIGS. 3A-3B illustrate re-using a classical register for a repeat-until-success loop in accordance with an embodiment of the present disclosure; FIGS. 4A-4C illustrate optimizing classical logic to minimize the feed-forward time in accordance with an embodiment of the present disclosure; FIGS. 5A-5B illustrate limiting a classical processor to not store greater than a maximum number of bits per time step or group of qubits in order to prevent crashing of the classical processor in accordance with an embodiment of the present disclosure; FIG. 6 illustrates an embodiment of the present disclosure of the hardware configuration of the classical computer which is representative of a hardware environment for practicing the present disclosure; and FIG. 7 is a flowchart of a method for improving transpilation of dynamic quantum circuits in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION As stated above, dynamic quantum circuits are quantum circuits with mid-circuit measurements and feed-forward classical operations which allow such circuits to be adaptive on-the-fly. A mid-circuit measurement is a quantum measurement at an intermediate point in the quantum circuit as opposed to a measurement at the end point of the quantum circuit thereby allowing dynamic adaptations based on the results. Feed-forward classical operations (or simply referred to herein as “feed-forward operations”) refer to the real-time adaptation of the quantum circuits based on earlier measurement outcomes. Dynamic quantum circuits are a fundamental part of utility-scale quantum computation (quantum utility is when a quantum computer is able to reliably solve problems at a scale that is beyond the capabilities of traditional classical computers using brute force methods), ranging from generating long-range entanglement more efficiently to executing core algorithmic primitives (e.g., quantum Fourier transform) to the foundation of active quantum error correction. Transpilation of quantum circuits, including dynamic quantum circuits, is a fundamental step in quantum computation. Transpilation, which is performed by a component referred to as a transpiler, is the process of rewriting a given input quantum circuit to match the topology of a specific quantum device, and optimize the circuit instructions for execution on noisy quantum computers. It optimizes the quantum circuit by decomposing