Phys.org July 30, 2024
Quantum systems of infinite dimension, such as bosonic oscillators, provide vast resources for quantum sensing. A general theory on how to manipulate such bosonic modes for sensing beyond parameter estimation is unknown. A team of researchers in the US (MIT, North Carolina State University) developed a general algorithmic framework, quantum signal processing interferometry (QSPI), for quantum sensing at the fundamental limits of quantum mechanics by generalizing Ramsey-type interferometry. The sensing protocol relied on performing nonlinear polynomial transformations on the oscillator’s quadrature operators by generalizing quantum signal processing (QSP) from qubits to hybrid qubit-oscillator systems. They used the QSPI sensing framework to make efficient binary decisions on a displacement channel in the single-shot limit. Theoretical analysis suggested the sensing accuracy scaled inversely with the sensing time or circuit depth of the algorithm. They concatenated a series of such binary decisions to perform parameter estimation in a bit-by-bit fashion, performing numerical simulations to support these statements. According to the researchers the 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… read more. Open Access TECHNICAL ARTICLE
Pictorial illustration of how in the bosonic QSP interferometry (QSPI) protocol… Credit: Quantum, volume 8, page 1427, 2024