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CRC Press eBooks

Quantum Sensors

Donati Silvano

Published Jun 20, 2023• 0 citations
Publisher

Abstract

A new perspective for photonic instrumentation is offered by quantum sensors. In the streamline of quantum computing, quantum sensors are based on some counter-intuitive properties of quantum optics, like squeezed states offering a measurement uncertainty below the normal quantum limit, and entangled states or bi-photons, pairing the result of measurements on photons propagated even very far away from each other. In the chapter, we describe at some length the squeezing of photons and its application to improved-sensitivity interferometry, and the basics of entangled states that potentially can also achieve performance at sub-quantum limit, even though till now they are limited to a speculative stage, although very promising.

DOI
10.1201/9781003391357-10

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A new perspective for photonic instrumentation is offered by quantum sensors. In the streamline of quantum computing, quantum sensors are based on some counter-intuitive properties of quantum optics, like squeezed states offering a measurement uncertainty below the normal quantum limit, and entangled states or bi-photons, pairing the result of measurements on photons propagated even very far away from each other. In the chapter, we describe at some length the squeezing of photons and its application to improved-sensitivity interferometry, and the basics of entangled states that potentially can also achieve performance at sub-quantum limit, even though till now they are limited to a speculative stage, although very promising.
Classical measurement strategies in many areas are approaching their maximum resolution and sensitivity levels, but these levels often still fall far short of the ultimate limits allowed by the laws of physics. To go further, strategies must be adopted that take into account the quantum nature of the probe particles and that optimize their quantum states for the desired application. Here, we review some of these approaches, in which quantum entanglement, the orbital angular momentum of single photons, and quantum interferometry are used to produce optical measurements beyond the classical limit.
Quantum optical sensing is a technique that utilizes quantum mechanics to enhance, sensitivity and precision to a level considered unparalleled so far. This chapter attempts to introduce the reader to the basics of this fast-growing field along with various technologies and applications. It begins with an explanation of quantum mechanics, superposition, entanglement, and quantum coherence that allow sensors to go beyond classical performance. One of the central technologies is quantum entanglement – the phenomenon whereby several particles become instantaneous spouses and are measured with utmost precision, for instance, distance, time, and magnetic fields. Entanglement Interferometry is entanglement applied in the detection of gravitational waves and high-resolution imaging. Squeezed light, the other area of interest, is a method that removes some of the fluctuations in one parameter of light, to increase the interferometer sensor, to measure small movements and low-frequency gravitational waves. Single photon emitting devices and detectors enable high-sensitivity measurements in applications such as bioimaging and quantum-securing communication. The chapter also illustrates the usage of this technology in practice in healthcare, environment, and navigation, like the examination of biomarkers and pollutants. Last is the discussion of issues such as quantum coherence and issues of scalability and development of QTs, as well as the proposed further development and more potential advances for QTs as a medium for mass use.
The minimum resolvable signal in sensing and metrology platforms that rely on optical readout fields is increasingly constrained by the standard quantum limit, which is determined by the sum of photon shot noise and back-action noise. A combination of back-action and shot noise reduction techniques will be critical to the development of the next generation of sensors for applications ranging from high-energy physics to biochemistry and for novel microscopy platforms capable of resolving material properties that were previously obscured by quantum noise. This Perspective reviews the dramatic advances made in the use of squeezed light for sub-shot-noise quantum sensing in recent years and highlights emerging applications that enable new science based on signals that would otherwise be obscured by noise at the standard quantum limit.
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This paper explores the potential of quantum metrology, specifically utilizing entangled photon pairs, to significantly enhance the precision of measurement systems. Traditional metrology is often limited by the fundamental precision constraints imposed by classical physics. Entanglement, a quantum mechanical phenomenon where two or more particles are linked in such a way that they share the same fate, regardless of the distance separating them, offers a pathway to overcome these limitations. This work details the theoretical framework for employing entangled photon pairs to minimize measurement noise and improve sensor accuracy. The core claim is that leveraging these correlations can provide a measurable advantage over classical techniques. The proposed mechanism focuses on reducing uncertainties associated with the measurement process by exploiting the inherent correlations between the entangled photons. The research targets applications like gravitational wave detection and biological imaging, where high precision is paramount. The paper presents a comprehensive overview of the theoretical concepts and potential advancements offered by this approach, laying the groundwork for future experimental investigations.
Quantum Mechanics has revolutionized not only our understanding of Nature but also, being the foundation of electronics and lasers, virtually all the instruments we use every day. Then again, we have not yet been able to harness the consequences of the most profoundly quantum phenomena such as state superpositions and particle entanglement. The Second Quantum Revolution has the ambition of building novel "quantum machines" able to fully exploit the properties of both microscopic and macroscopic quantum states. Quantum sensors, making use of the phenomenon of entanglement in systems promise to reach the fundamental measurement limits determined by the laws of physics and correspondingly improve the current performance of the sensors by orders of magnitude in terms of precision and accuracy, with important application implications in the scientific, industrial, and commercial fields. They can measure with unprecedented precision a wide class of physical quantities, such as magnetic, electric, and inertial fields, times, frequencies, temperatures and pressures.