High-resolution Quantum Sensing Enables 4x 10⁻⁶ °C Temperature Measurement

High-resolution sensing represents a crucial challenge across many areas of science and technology, yet current methods face fundamental limitations. Qi-An Su, Qi Song, and Hongjing Li, alongside colleagues including Jingzheng Huang from Shanghai Jiao Tong University, now present a new approach to overcome these constraints. Their research establishes a sensing technique based on discriminating between quantum states, but crucially, it constructs measurements in a different way than previous methods, focusing on the space outside the expected signal. This innovative strategy significantly enhances the ability to distinguish between closely spaced states, and experiments using an optical microcavity demonstrate a potential resolution of 4x 10⁻⁶ °C for temperature and 18 picostrains for strain, while also proving the possibility of measuring both parameters simultaneously. This work provides a versatile framework for high-resolution sensing, paving the way for applications across diverse fields and platforms.

Quantum Parameter Estimation via State Discrimination

Scientists developed a novel high-resolution sensing approach founded on the principles of quantum state discrimination, addressing limitations inherent in conventional sensing techniques. The study pioneers a method that encodes unknown parameters onto quantum states and then employs quantum state discrimination to precisely identify and extract those parameters, achieving significantly improved sensitivity. Unlike traditional approaches, this work constructs measurement operators within the orthogonal complement space of the quantum states, markedly enhancing the ability to distinguish between closely related quantum states. The research team engineered a four-stage process beginning with quantum state evolution, where an unknown parameter vector is encoded into an initial quantum state, transforming it into a new state reflecting the parameters’ values.

Subsequently, the evolved state undergoes measurement using pre-defined operators designed to quantify the probability of the quantum state residing within the orthogonal complement subspace. This innovative use of the orthogonal complement space allows for greater differentiation between states that would otherwise appear similar, particularly when dealing with small parameter variations. To quantitatively assess the dissimilarity between the unknown state and pre-calibrated states, scientists defined a sensitivity factor based on the probability distance between them within the orthogonal complement subspace. This factor, calculated using matrix products, effectively characterizes the difference in occupancy probabilities, enabling precise identification of the unknown state.

The team then implemented an algorithm to identify the unknown state by determining the maximum sensitivity factor, effectively mapping parameters to distinct eigenspaces for discrete representation. Experiments employing a whispering gallery mode microcavity platform demonstrate the practical application of this method, achieving a temperature resolution of 4x 10⁻⁶ °C and a strain resolution of 18 pε in single-parameter sensing. Furthermore, the study confirms the capability for simultaneous temperature and strain sensing, establishing a universal approach for high-resolution sensing applicable across diverse platforms and scenarios.,.

Quantum Sensing Achieves Micro-Degree Temperature Resolution

Scientists have developed a novel high-resolution sensing approach based on quantum state discrimination, achieving unprecedented levels of precision in temperature and strain measurements. This work establishes a new methodology for parameter sensing by encoding unknown parameters onto quantum states and then employing optimized measurement techniques to extract the desired information. The core breakthrough lies in constructing measurement operators within the orthogonal complement space of the quantum states, rather than the conventional eigenspace, significantly enhancing the ability to distinguish between closely-spaced quantum states. Experiments conducted using an optical microcavity platform demonstrate a remarkable sensing resolution of 4x 10⁻⁶ °C for temperature, representing a substantial improvement over existing technologies.

Simultaneously, the team measured strain with a resolution of 18 picostrains (pε), confirming the feasibility of simultaneously sensing both parameters with high accuracy. The method involves encoding the unknown parameter into the initial quantum state, followed by measurement using the specifically designed operators, and ultimately retrieving the parameter value through quantum state determination. This innovative approach overcomes limitations inherent in traditional sensing methods, such as spectral resolution limits caused by spontaneous emission and the challenges of cross-sensitivity in distributed fiber sensing. By leveraging the principles of quantum state discrimination, the researchers maximized the distinguishability of quantum states, enabling the detection of exceedingly small changes in temperature and strain.,.

Enhanced Sensing via Orthogonal State Discrimination

This research presents a novel high-resolution sensing approach founded on the principles of quantum state discrimination, achieving significant improvements over conventional methods. By constructing measurement operators in the orthogonal complement space of quantum states, rather than the traditionally used eigenspace, scientists markedly enhanced the ability to distinguish between closely spaced states. Experimental validation, utilising an optical microcavity, demonstrates a potential sensing resolution of 4x 10⁻⁶ °C for temperature and 18 pico-strain for strain, alongside the successful simultaneous measurement of both parameters. The team’s method establishes a versatile framework applicable to diverse sensing platforms and scenarios, moving beyond the limitations imposed by conventional techniques. While current experiments are constrained by the number of distinguishable quantum states achievable with existing instrumentation, the researchers note that resolution progressively improves with optimisation of the microcavity quality factor. Future work may involve integrating the approach with alternative sensing platforms, such as fiber microcavities and photonic crystals, broadening its applicability to areas including wearable physiological monitoring, intelligent electronic skins, and materials science.