Quantum Signal Processing Interferometry: Pushing the Limits of Sensing with Quantum Algorithms

Quantum systems of infinite dimension, such as bosonic oscillators, provide vast resources for quantum sensing. Yet, a general theory on how to manipulate such bosonic modes for sensing beyond parameter estimation is unknown. We present a general algorithmic framework, quantum signal processing interferometry (QSPI), for quantum sensing at the fundamental limits of quantum mechanics by generalizing Ramsey-type interferometry. Our QSPI sensing protocol relies on performing nonlinear polynomial transformations on the oscillator’s quadrature operators by generalizing quantum signal processing (QSP) from qubits to hybrid qubit-oscillator systems. We use our QSPI sensing framework to make efficient binary decisions on a displacement channel in the single-shot limit. Theoretical analysis suggests the sensing accuracy, given a single-shot qubit measurement, scales inversely with the sensing time or circuit depth of the algorithm. We further concatenate a series of such binary decisions to perform parameter estimation in a bit-by-bit fashion. Numerical simulations are performed to support these statements. Our QSPI protocol offers a unified framework for quantum sensing using continuous-variable bosonic systems beyond parameter estimation and establishes a promising avenue toward efficient and scalable quantum control and quantum sensing schemes beyond the NISQ era.

Yuan Liu

Assistant Professor, NC State University on August 23, 2024 at 10:15 AM in EB2 1231
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Dr. Liu is an Assistant Professor of Electrical & Computer Engineering and Computer Science at North Carolina State University. He is also an affiliated faculty in Physics. He received his B.S. in physics from Tsinghua University in Beijing. He received his M.S. in electrical engineering and a Ph.D. in chemical physics from Brown University in Providence, Rhode Island. Prior to joining NC State faculty in January 2024, he was a postdoctoral researcher at the Massachusetts Institute of Technology. His research interests lie at the intersection of quantum information science, theoretical chemistry and physics, and quantum engineering.

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