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We propose a measurement-based quantum metrology protocol in a composite model, where the probe system (a spin ensemble) is coupled to an ancillary two-level system (qubit) with a general Heisenberg XXZ interaction. With an optimized and…

Quantum Physics · Physics 2026-01-23 Peng Chen , Jun Jing

Low-frequency qubit control wires require non-trivial thermal anchoring and low-pass filtering. The resulting electron temperature serves as a quality benchmark for these signal lines. In this technical note, we make use of a primary…

Mesoscale and Nanoscale Physics · Physics 2024-04-16 Elias Roos Hansen , Ferdinand Kuemmeth , Joost van der Heijden

We address the dephasing dynamics of a qubit as an effective process to estimate the temperature of its environment. Our scheme is inherently quantum, since it exploits the sensitivity of the qubit to decoherence, and does not require…

Quantum systems used for metrology can offer enhanced precision over their classical counterparts. The design of quantum sensors can be optimized by maximizing the quantum Fisher information (QFI), which characterizes the precision of…

Quantum Physics · Physics 2025-08-26 George Mihailescu , Anthony Kiely , Andrew K. Mitchell

Precise thermometry for quantum systems is important to the development of new technology, and understanding the ultimate limits to precision presents a fundamental challenge. It is well known that optimal thermometry requires projective…

Quantum Fisher information (QFI) is a novel measure of multipartite quantum entanglement that can be measured in inelastic neutron scattering experiments on quantum magnets. In this work, we demonstrate that the QFI can be used to…

Strongly Correlated Electrons · Physics 2025-10-17 Chengkang Zhou , Zhengbang Zhou , Félix Desrochers , Yong Baek Kim , Zi Yang Meng

We use the theory of quantum estimation in two different qubit-boson coupling models to demonstrate that the temperature of a quantum harmonic oscillator can be estimated with high precision by quantum-limited measurements on the qubit. The…

Quantum Physics · Physics 2012-10-31 Matteo Brunelli , Stefano Olivares , Mauro Paternostro , Matteo G. A. Paris

While the ability to measure low temperatures accurately in quantum systems is important in a wide range of experiments, the possibilities and the fundamental limits of quantum thermometry are not yet fully understood theoretically. Here we…

Quantum Physics · Physics 2019-07-10 Patrick P. Potts , Jonatan Bohr Brask , Nicolas Brunner

We address a particular instance where open quantum systems may be used as quantum probes for an emergent property of a complex system, as the temperature of a thermal bath. The inherent fragility of the quantum probes against decoherence…

The temperature sensitivity of a probe in equilibrium can be gauged by its thermal quantum Fisher information (QFI). It is known that probes exhibiting degeneracy in their energy-level structure can achieve larger sensitivities, while…

Quantum Physics · Physics 2026-02-16 Tabitha Doicin , Luis A. Correa , Jonas Glatthard , Andrew D. Armour , Gerardo Adesso

The fundamental metrological limits of temperature sensing in open quantum systems remain largely unresolved, particularly regarding the role of non-Gaussian quantum resources. In this letter, we establish analytic bounds on the quantum…

Quantum Physics · Physics 2025-12-04 Pritam Chattopadhyay

Temperature estimation of interacting quantum many-body systems is both a challenging task and topic of interest in quantum metrology, given that critical behavior at phase transitions can boost the metrological sensitivity. Here we study…

Quantum Physics · Physics 2023-12-05 Mei Yu , H. Chau Nguyen , Stefan Nimmrichter

Thermal equilibrium states are exponentially hard to distinguish at very low temperatures, making equilibrium quantum thermometry in this regime a formidable task. We present a thermometric scheme that circumvents this limitation, by using…

Quantum Physics · Physics 2021-10-07 Ivan Henao , Karen V. Hovhannisyan , Raam Uzdin

We introduce the estimation protocol for detecting the temperature of the transverse vibrational modes of linear ion crystal. We show that thanks to the laser induced laser coupling between the vibrational modes and the collective spin…

Quantum Physics · Physics 2018-12-26 Peter A. Ivanov

Measuring the temperature of a quantum system is an essential task in almost all aspects of quantum technologies. Theoretically, an optimal strategy for thermometry requires measuring energy which demands full accessibility over the entire…

Quantum Physics · Physics 2024-03-18 Yaoling Yang , Victor Montenegro , Abolfazl Bayat

In the scenario of the probe-ancilla interaction, we propose a quantum metrology protocol by the unconditional measurement on the ancillary qubit after an optimized period of joint evolution from product state. Its key element is the…

Quantum Physics · Physics 2025-09-12 Peng Chen , Jun Jing

We describe and analyze a quantum thermometer based on a multilayered collisional model. We propose a qubit system whose architecture provides significant sensitivity even for short interaction times between the ancillae that compose the…

Quantum Physics · Physics 2025-12-02 Taysa M. Mendonça , Diogo O. Soares-Pinto , Mauro Paternostro

Quantum metrology is being gradually studied for weak measurement systems. For weak measurement systems with thermal state pointer, we find that in the displacement space corresponding to imaginary weak values, the maximal QFI after…

Quantum Physics · Physics 2018-11-13 Gang Li , Li-Bo Chen , Tao Wang , Zhi-Hui He , He-Shan Song

We characterise the measurement sensitivity, quantified by the Quantum Fisher Information (QFI), of a single-fermionic thermometric probe strongly coupled to the sample of interest, a fermionic bath, at temperature $T$. For nonequilibrium…

We consider the problem of estimating the temperature $ T $ of a very cold equilibrium sample. The temperature estimates are drawn from measurements performed on a quantum probe strongly coupled to it. We model this scenario by resorting to…