High-Resolution Sensing via Quantum States Discrimination

Abstract

High-resolution sensing plays a significant role in scientific research and industrial production, but the practical implementation is constrained by the physical mechanisms of the sensors. To address the critical limitation, we propose a high-resolution sensing approach based on quantum state discrimination. Distinct from conventional strategies, the proposed approach constructs measurement operators in the orthogonal complement space rather than eigenspace of the eigenstate, thereby notably improving the discriminability among quantum states. Moreover, the experimental results via an optical microcavity demonstrate a potential sensing resolution of 4 $\times$ 10\textsuperscript{-6} \degree C and 18 p$ε$ respectively for temperature and strain, and further verify the feasibility of simultaneous sensing of the two parameters. This work establishs a universal approach for high-resolution sensing, and may be extended to different sensing platforms across various application scenarios.

Figures (3)

• Figure 1: The basic concept of quantum state discrimination. a Quantum state discrimination process. It consists of four stages: quantum state evolution, measurement via pre-defined measurement operators, sensitivity factor generation and parameter retrieval via quantum state discrimination. b Schematic illustration of the eigenspace and orthogonal complement space. The entire sphere represents the total eigenspace $\mathcal{H}$ encompassing all quantum states. Taking three eigenspaces as an example, the planes within the sphere represent individual eigenspace $\mathcal{H}^{(k)}$, while the dots within the planes mark the possible positions of quantum state $\rho^{(k)}$. The regions of the sphere excluding the planes correspond to orthogonal complement space $\mathcal{H}_{\bot}^{{(k)}}$.
• Figure 2: Conceptual design and experimental setup. a Conceptual design. b Experimental setup. The abbreviations are as follows: SLD: superluminescent diode; FBS: fiber beam splitter; PC: polarization controller; WGM: whispering gallery mode microcavity; DAC: data acquisition card. c Visualization of transmission spectra under two sets of conditions: varying strains at a fixed temperature, and a fixed strain at varying temperatures. Distinct positions corresponding to different frequencies and colors indicating the magnitude at each frequency. The meanings of the letters are as follows: T: temperature, S: strain.
• Figure 3: The distribution of sensitivity factors under different conditions. a The distribution of sensitivity factor for temperature sensing under two kinds of resolutions. b The distribution of sensitivity factor for strain sensing under two kinds of resolutions. c The distribution of sensitivity factor under $\textbf{M}_{\bot}$. d The distribution of sensitivity factor under $\textbf{M}$.