Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2604.00231

100 years of spin: fundamental physics, dark matter, exotic interactions, and all that

Dmitry Budker, Tim Chupp, Klaus Kirch, W. Mike Snow

quant-phhep-phSubmitted Mar 31, 2026• Announced Apr 2, 2026
arXivHTMLPDF

Abstract

For a century, spin has been an indispensable probe of the fundamental laws of nature. A reflection on the role of spin in shaping modern physics is presented, from the early days of quantum mechanics to the latest precision tests of the Standard Model. The significance of magnetic and electric dipole moments in testing CP and CPT symmetries is surveyed, along with the ongoing searches for exotic spin-dependent interactions that may reveal the nature of dark matter and its connection to spacetime geometry. Through these vignettes, it is shown that spin continues to provide a fresh perspective on the most profound questions in physics today.

Related papers

Quantum Sensors for High Precision Measurements of Spin-dependent Interactions

Dmitry Budker, T. Cecil, T. E. Chupp +6 more

The applications of spin-based quantum sensors to measurements probing fundamental physics are surveyed. Experimental methods and technologies developed for quantum information science have rapidly advanced in recent years, and these tools enable increasingly precise control and measurement of spin dynamics. Theories of beyond-the-Standard-Model physics predict, for example, symmetry violating electromagnetic moments aligned with particle spins, exotic spin-dependent forces, coupling of spins to ultralight bosonic dark matter fields, and changes to the local environment that affect spins. Spin-based quantum sensors can be used to search for these myriad phenomena, and offer a methodology for tests of fundamental physics that is complementary to particle colliders and large scale particle detectors. Areas of technological development that can significantly enhance the sensitivity of spin-based quantum sensors to new physics are highlighted.

arXiv:2203.09488•Mar 17, 2022•4 citations

Probing fundamental physics with spin-based quantum sensors

Derek F. Jackson Kimball, Dmitry Budker, T. E. Chupp +4 more

The applications of spin-based quantum sensors to measurements probing fundamental physics are surveyed. Experimental methods and technologies developed for spin-based quantum information science have rapidly advanced in recent years and these tools enable increasingly precise control and measurement of spin dynamics. Theories of beyond-the-standard-model physics predict, for example, discrete-symmetry-violating electromagnetic moments correlated with particle spins, exotic spin-dependent forces, and coupling of spins to ultralight bosonic dark-matter fields. Spin-based quantum sensors can be used to search for these myriad phenomena and offer a methodology for tests of fundamental physics that is complementary to particle colliders and large-scale particle detectors. Areas of technological development that can significantly enhance the sensitivity of spin-based quantum sensors to new physics are highlighted.Received 30 January 2023DOI:https://doi.org/10.1103/PhysRevA.108.010101©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAxionsOptical pumpingParticle dark matterQuantum measurementsQuantum metrologyTests of fundamental symmetriesZeeman effectAtomic, Molecular & OpticalParticles & FieldsQuantum Information

Physical Review A•Jul 17, 2023•49 citations

The Wonder of Quantum Spin

Indubala I. Satija

Abstract The Wonder of Quantum Spin is a confection of the history and the science of quantum spin covering two centuries of the golden era in mathematics and physics. First glimpses of spin appeared nearly 200 years ago in the study of rotations where spinors emerged as a new entity that changes sign after a 360 degree rotation, reminiscent of the Mobius geometry. A century later, quantum spin described by the spinor was discovered in physics. Among many other things, it led to the discovery of antimatter, raised the possibility of parity violation, and gave the first warning that protons and neutrons are not elementary. The MRI—one of the most important medical advances of the twentieth century—is an application of quantum spin to humanity. As we approach the centennial of the discovery of spin in Nature, the spin mystique prevails as we have no clue of what exactly spinning is. On the other hand, the theoretical framework underlying the spin determines why we exist, explains the mysteries of the 3000 years-old phenomena of magnetism, is behind the precision measurements of electron and muon spin magnetic moments displaying a mindboggling confrontation between theory and experiment that serves as an ambassador to quantum physics. Some of the other frontiers of physics that revolve around spin-1/2 include exotic states of matter known as topological insulators and the qubit—the quantum bits for tomorrow’s computers.

•Jun 25, 2024•0 citations

Understanding Spin: the field theory of magnetic interactions

Werner A. Hofer

Spin is commonly thought to reflect the true quantum nature of microphysics. We show that spin is related to intrinsic and field-like properties of single particles. These properties change continuously in external magnetic fields. Interactions of massive particles with homogeneous and inhomogeneous fields result in two discrete particle states, symmetric to the original one. We analyze the difficulties in quantum mechanics to give a precise spacetime account of the experiments and find that they arise from unsuitable analogies for spin. In particular from the analogy of an angular momentum. Several experiments are suggested to check the model against the standard model in quantum mechanics.

arXiv:quant-ph/0009083•Sep 21, 2000•0 citations

From the Single Electron to Spin

Plinio Innocenzi

The nature of the electron, a point particle according to the Standard Model, presents a paradox that challenges our ability to comprehend the physical reality. This paradox lies in the apparent contradiction between the complexity represented according to mathematical models that fully describe experimental results and the world around us perceived as a representation of an intuitive process. For example, how come all electrons are the same? As we shall see in this chapter, a seemingly simple question stimulated original reflections that later led to significant theoretical developments. Stern and Gerlach’s experiments demonstrated that the electron possesses an intrinsic property, the spin, whose generalization led to the distinction between fermions and bosons. The spin property, however, is apparently not reconcilable with the point properties of the electron. It has, in fact, not any analogue in classical physics. This incongruence also applies to the electron’s magnetic dipole moment. The key to everything is perhaps the spin property, which has Pauli’s Exclusion Principle as its consequence, to which we owe the existence of matter as we perceive it.

Springer eBooks•Jan 1, 2025•0 citations

A Short History of Spin

R. Milner

The paper outlines the historical development of spin in physics from about 1920 to the present day. It aims to provide the student with an accurate chronology of important developments, both scientific and technical.

arXiv:1311.5016•Nov 20, 2013•0 citations
For a century, spin has been an indispensable probe of the fundamental laws of nature. A reflection on the role of spin in shaping modern physics is presented, from the early days of quantum mechanics to the latest precision tests of the Standard Model. The significance of magnetic and electric dipole moments in testing CP and CPT symmetries is surveyed, along with the ongoing searches for exotic spin-dependent interactions that may reveal the nature of dark matter and its connection to spacetime geometry. Through these vignettes, it is shown that spin continues to provide a fresh perspective on the most profound questions in physics today.
The applications of spin-based quantum sensors to measurements probing fundamental physics are surveyed. Experimental methods and technologies developed for quantum information science have rapidly advanced in recent years, and these tools enable increasingly precise control and measurement of spin dynamics. Theories of beyond-the-Standard-Model physics predict, for example, symmetry violating electromagnetic moments aligned with particle spins, exotic spin-dependent forces, coupling of spins to ultralight bosonic dark matter fields, and changes to the local environment that affect spins. Spin-based quantum sensors can be used to search for these myriad phenomena, and offer a methodology for tests of fundamental physics that is complementary to particle colliders and large scale particle detectors. Areas of technological development that can significantly enhance the sensitivity of spin-based quantum sensors to new physics are highlighted.
The applications of spin-based quantum sensors to measurements probing fundamental physics are surveyed. Experimental methods and technologies developed for spin-based quantum information science have rapidly advanced in recent years and these tools enable increasingly precise control and measurement of spin dynamics. Theories of beyond-the-standard-model physics predict, for example, discrete-symmetry-violating electromagnetic moments correlated with particle spins, exotic spin-dependent forces, and coupling of spins to ultralight bosonic dark-matter fields. Spin-based quantum sensors can be used to search for these myriad phenomena and offer a methodology for tests of fundamental physics that is complementary to particle colliders and large-scale particle detectors. Areas of technological development that can significantly enhance the sensitivity of spin-based quantum sensors to new physics are highlighted.Received 30 January 2023DOI:https://doi.org/10.1103/PhysRevA.108.010101©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAxionsOptical pumpingParticle dark matterQuantum measurementsQuantum metrologyTests of fundamental symmetriesZeeman effectAtomic, Molecular & OpticalParticles & FieldsQuantum Information
Abstract The Wonder of Quantum Spin is a confection of the history and the science of quantum spin covering two centuries of the golden era in mathematics and physics. First glimpses of spin appeared nearly 200 years ago in the study of rotations where spinors emerged as a new entity that changes sign after a 360 degree rotation, reminiscent of the Mobius geometry. A century later, quantum spin described by the spinor was discovered in physics. Among many other things, it led to the discovery of antimatter, raised the possibility of parity violation, and gave the first warning that protons and neutrons are not elementary. The MRI—one of the most important medical advances of the twentieth century—is an application of quantum spin to humanity. As we approach the centennial of the discovery of spin in Nature, the spin mystique prevails as we have no clue of what exactly spinning is. On the other hand, the theoretical framework underlying the spin determines why we exist, explains the mysteries of the 3000 years-old phenomena of magnetism, is behind the precision measurements of electron and muon spin magnetic moments displaying a mindboggling confrontation between theory and experiment that serves as an ambassador to quantum physics. Some of the other frontiers of physics that revolve around spin-1/2 include exotic states of matter known as topological insulators and the qubit—the quantum bits for tomorrow’s computers.
Spin is commonly thought to reflect the true quantum nature of microphysics. We show that spin is related to intrinsic and field-like properties of single particles. These properties change continuously in external magnetic fields. Interactions of massive particles with homogeneous and inhomogeneous fields result in two discrete particle states, symmetric to the original one. We analyze the difficulties in quantum mechanics to give a precise spacetime account of the experiments and find that they arise from unsuitable analogies for spin. In particular from the analogy of an angular momentum. Several experiments are suggested to check the model against the standard model in quantum mechanics.
The nature of the electron, a point particle according to the Standard Model, presents a paradox that challenges our ability to comprehend the physical reality. This paradox lies in the apparent contradiction between the complexity represented according to mathematical models that fully describe experimental results and the world around us perceived as a representation of an intuitive process. For example, how come all electrons are the same? As we shall see in this chapter, a seemingly simple question stimulated original reflections that later led to significant theoretical developments. Stern and Gerlach’s experiments demonstrated that the electron possesses an intrinsic property, the spin, whose generalization led to the distinction between fermions and bosons. The spin property, however, is apparently not reconcilable with the point properties of the electron. It has, in fact, not any analogue in classical physics. This incongruence also applies to the electron’s magnetic dipole moment. The key to everything is perhaps the spin property, which has Pauli’s Exclusion Principle as its consequence, to which we owe the existence of matter as we perceive it.