CS Events Monthly View

Qualifying Exam

Efficient Quantum Circuit Compilation with Permutable Operators through a Time-Optimal SWAP Insertion Approach

 

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Tuesday, May 09, 2023, 10:00am - 12:00pm

 

Abstract:

In the NISQ era of quantum computing, each qubit is physically connected to a limited number of neighboring qubits. This limitation requires a compiler to convert a quantum program into a hardware-compliant circuit, specifically, by mapping each two-qubit gate to two physical qubits connected by a link.  Existing approaches use SWAP gates to dynamically remap logical qubits to physical qubits, but often lack consideration for time-optimality. We propose a theoretically time-optimal SWAP insertion scheme for the qubit mapping problem. Later, the Quantum Approximation Optimization Algorithm (QAOA) gained attention as a highly advocated variational algorithm for solving combinatorial optimization problems. One critical feature of the QAOA quantum circuit is that it consists of permutable two-qubit operators that commute. The flexibility in ordering these permutable gates leads to shorter circuit depth but presents a challenge in circuit compilation due to the additional degree of freedom. To utilize this flexibility, we adapt our SWAP insertion scheme for generic circuits and propose a structured solution that considers connectivity regularity in scalable quantum hardware. We also adapt this structured method to practical cases in real hardware, addressing sparsity of input problem graphs and noise variability. We evaluate our method on IBM and Google architecture coupling graphs for up to 1,024 qubits and demonstrate better results in both depth and gate count, with up to a 72% reduction in depth and a 66% reduction in gate count. Our real experiments on IBM Mumbai show that we can find a better expected minimal energy than the state-of-the-art baseline.

 

Speaker: Yuwei Jin

Location : CoRE 305

Committee

Professor Zheng Zhang (Advisor)

Professor Yipeng Huang

Professor Mario Szegedy

Professor Casimir Kulikowski

 

Event Type: Qualifying Exam

Abstract: See above

Organization

Rutgers University

School of Arts & Sciences

Department of Computer Science

 

Contact  Professor Zheng Zhang