Lucien Hardy

Last updated
Lucien Hardy
Alma mater Durham University (PhD)
Known for Hardy's paradox
Scientific career
Fields Quantum foundations
Quantum information
Quantum gravity
Institutions University of Waterloo
Thesis Nonlocality, violation of lorentz in variance, and wave-particle duality in quantum theory  (1992)
Doctoral advisor Euan J. Squires
Website https://perimeterinstitute.ca/people/lucien-hardy

Lucien Hardy (born 1966) is a British-Canadian theoretical physicist currently based at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

Contents

Hardy is best known for his work on the foundation of quantum physics, including the Hardy's paradox thought experiment, and his influential work in quantum field theory, which seeks to reconcile quantum mechanics to general relativity. [1] [2]

Education

Hardy studied for his doctorate at Durham University (1989–1992) under the supervision of Euan J. Squires. [3]

Work

In 1992, he became lecturer in mathematical physics at Maynooth College, part of The National University of Ireland. He was subsequently a Royal Society postdoctoral fellow at the University of Innsbruck (1993–1994), then returned to Durham as Lecturer (1994–1996), and was a postdoctoral fellow at La Sapienza University (1996–1997). [4]

Starting in 1997, he was a Royal Society University Research Fellow at the University of Oxford until 2002. [4]

Hardy is now affiliated with the University of Waterloo and is among the faculty of the Perimeter Institute for Theoretical Physics. [4]

Hardy's Paradox

In 1992, Hardy published a thought experiment that "makes nonsense of the famous interaction between matter and antimatter" — that when a particle meets its antiparticle, the pair "always annihilate one another" in a burst of energy. [5] Hardy proposed the possibility that in some cases when said interaction is not observed a particle and an antiparticle could interact with one another and survive. But since the interaction has to remain unseen, no one would notice this happening, which is why the result came to be known as Hardy's paradox. [6] [7] [5]

Five Reasonable Axioms

In 2001, Hardy published Quantum Theory From Five Reasonable Axioms, a paper that offered an axiomatic reconstruction of quantum theory. His proposal represented an "operational" approach made famous by Albert Einstein, but applied to quantum mechanics. [2]

In subsequent years, other authors built upon Hardy's work by proposing their own variants. [8] [9]

Related Research Articles

<span class="mw-page-title-main">Quantum entanglement</span> Correlation between measurements of quantum subsystems, even when spatially separated

Quantum entanglement is the phenomenon that occurs when a group of particles are generated, interact, or share spatial proximity in a way such that the quantum state of each particle of the group cannot be described independently of the state of the others, including when the particles are separated by a large distance. The topic of quantum entanglement is at the heart of the disparity between classical and quantum physics: entanglement is a primary feature of quantum mechanics not present in classical mechanics.

<span class="mw-page-title-main">Standard Model</span> Theory of forces and subatomic particles

The Standard Model of particle physics is the theory describing three of the four known fundamental forces in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.

Charge, parity, and time reversal symmetry is a fundamental symmetry of physical laws under the simultaneous transformations of charge conjugation (C), parity transformation (P), and time reversal (T). CPT is the only combination of C, P, and T that is observed to be an exact symmetry of nature at the fundamental level. The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry.

<span class="mw-page-title-main">Steven Weinberg</span> American theoretical physicist (1933–2021)

Steven Weinberg was an American theoretical physicist and Nobel laureate in physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and electromagnetic interaction between elementary particles.

<span class="mw-page-title-main">Olaf Dreyer</span> German physicist

Olaf Dreyer is a German theoretical physicist whose research interests include quantum gravity and the quantum measurement problem. Dreyer received his Ph.D. in quantum gravity in 2001 from the Pennsylvania State University under the direction of Abhay Ashtekar. Subsequently, he has held a postdoctoral fellowship at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, a Marie Curie Fellowship at Imperial College, London, and a postdoctoral fellowship at the Center for Theoretical Physics, Massachusetts Institute of Technology.

A Bell test, also known as Bell inequality test or Bell experiment, is a real-world physics experiment designed to test the theory of quantum mechanics in relation to Albert Einstein's concept of local realism. Named for John Stewart Bell, the experiments test whether or not the real world satisfies local realism, which requires the presence of some additional local variables to explain the behavior of particles like photons and electrons. To date, all Bell tests have found that the hypothesis of local hidden variables is inconsistent with the way that physical systems behave.

<span class="mw-page-title-main">History of quantum field theory</span>

In particle physics, the history of quantum field theory starts with its creation by Paul Dirac, when he attempted to quantize the electromagnetic field in the late 1920s. Heisenberg was awarded the 1932 Nobel Prize in Physics "for the creation of quantum mechanics". Major advances in the theory were made in the 1940s and 1950s, leading to the introduction of renormalized quantum electrodynamics (QED). QED was so successful and accurately predictive that efforts were made to apply the same basic concepts for the other forces of nature. By the late 1970s, these efforts successfully utilized gauge theory in the strong nuclear force and weak nuclear force, producing the modern Standard Model of particle physics.

In theoretical physics, statistical field theory (SFT) is a theoretical framework that describes phase transitions. It does not denote a single theory but encompasses many models, including for magnetism, superconductivity, superfluidity, topological phase transition, wetting as well as non-equilibrium phase transitions. A SFT is any model in statistical mechanics where the degrees of freedom comprise a field or fields. In other words, the microstates of the system are expressed through field configurations. It is closely related to quantum field theory, which describes the quantum mechanics of fields, and shares with it many techniques, such as the path integral formulation and renormalization. If the system involves polymers, it is also known as polymer field theory.

<span class="mw-page-title-main">François Englert</span> Belgian theoretical physicist

François, Baron Englert is a Belgian theoretical physicist and 2013 Nobel Prize laureate.

Steven C. Frautschi is an American theoretical physicist, currently professor of physics emeritus at the California Institute of Technology (Caltech). He is known principally for his contributions to the bootstrap theory of the strong interactions and for his contribution to the resolution of the infrared divergence problem in quantum electrodynamics (QED). He was named a Fellow of the American Physical Society in 2015 for "contributions to the introduction of Regge poles into particle physics, elucidation of the role of infrared photons in high energy scattering, and for seminal contributions to undergraduate physics education".

Hardy's paradox is a thought experiment in quantum mechanics devised by Lucien Hardy in 1992–1993 in which a particle and its antiparticle may interact without annihilating each other.

Jean Zinn-Justin is a French theoretical physicist.

{{Infobox scientist | name = Ramamurti Rajaraman | image = | image_size = | caption = | birth_date = 11 March 1939 | birth_place = | death_date = | death_place = | citizenship = | nationality = Indian | field = Physics | work_institution = Jawaharlal Nehru University | alma_mater = St. Stephen's College, Delhi (B.Sc.)
Cornell University (PhD) | doctoral_advisor = Hans Bethe | academic_advisors = | doctoral_students = | known_for = | author_abbrev_bot = | author_abbrev_zoo = | influences = | awards = 1983 [[Shanti Swarup Bhatnagar Prize for Science and Technology | signature = | footnotes = | website = }}

<span class="mw-page-title-main">Sandu Popescu</span> British physicist

Sandu Popescu is a Romanian-British physicist working in the foundations of quantum mechanics and quantum information.

Freddy Alexander Cachazo is a Venezuelan-born theoretical physicist who holds the Gluskin Sheff Freeman Dyson Chair in Theoretical Physics at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada.

Quantum foundations is a discipline of science that seeks to understand the most counter-intuitive aspects of quantum theory, reformulate it and even propose new generalizations thereof. Contrary to other physical theories, such as general relativity, the defining axioms of quantum theory are quite ad hoc, with no obvious physical intuition. While they lead to the right experimental predictions, they do not come with a mental picture of the world where they fit.

<span class="mw-page-title-main">Giacomo Mauro D'Ariano</span> Italian quantum physicist

Giacomo Mauro D'Ariano is an Italian quantum physicist. He is a professor of theoretical physics at the University of Pavia, where he is the leader of the QUIT group. He is a member of the Center of Photonic Communication and Computing at Northwestern University; a member of the Istituto Lombardo Accademia di Scienze e Lettere; and a member of the Foundational Questions Institute (FQXi).

Adrian Kent is a British theoretical physicist, Professor of Quantum Physics at the University of Cambridge, member of the Centre for Quantum Information and Foundations, and Distinguished Visiting Research Chair at the Perimeter Institute for Theoretical Physics. His research areas are the foundations of quantum theory, quantum information science and quantum cryptography. He is known as the inventor of relativistic quantum cryptography. In 1999 he published the first unconditionally secure protocols for bit commitment and coin tossing, which were also the first relativistic cryptographic protocols. He is a co-inventor of quantum tagging, or quantum position authentication, providing the first schemes for position-based quantum cryptography. In 2005 he published with Lucien Hardy and Jonathan Barrett the first security proof of quantum key distribution based on the no-signalling principle.

Ivette Fuentes is a Professor of Quantum Physics at the University of Southampton and Professor of Theoretical Quantum Optics at the University of Vienna. Her work considers fundamental quantum mechanics, quantum optics and astrophysics. She is interested in how quantum information theory can make use of relativistic effects.

A generalized probabilistic theory (GPT) is a general framework to describe the operational features of arbitrary physical theories. A GPT must specify what kind of physical systems one can find in the lab, as well as rules to compute the outcome statistics of any experiment involving labeled preparations, transformations and measurements. The framework of GPTs has been used to define hypothetical non-quantum physical theories which nonetheless possess quantum theory's most remarkable features, such as entanglement or teleportation. Notably, a small set of physically motivated axioms is enough to single out the GPT representation of quantum theory.

References

  1. Clark, Joanne (25 March 2019). "Lucien Hardy: Thought, Matter, and Quantum Theory". The Ludmer Centre. Retrieved 6 May 2023.
  2. 1 2 Wolchover, Natalie (11 March 2021). "Quantum Mischief Rewrites the Laws of Cause and Effect". Quanta. Retrieved 6 May 2023.
  3. Lucien Hardy at the Mathematics Genealogy Project
  4. 1 2 3 "Lucien Hardy". Perimeter Institute. Retrieved 6 May 2023.
  5. 1 2 "I'm not looking, honest!". The Economist . 7 March 2009. Retrieved 6 May 2023.
  6. Hardy, Lucien (1992). "Quantum mechanics, local realistic theories, and Lorentz-invariant realistic theories". Physical Review Letters. 68 (20): 2981–2984. Bibcode:1992PhRvL..68.2981H. doi:10.1103/PhysRevLett.68.2981. PMID   10045577.
  7. Hardy, Lucien (1993). "Nonlocality for two particles without inequalities for almost all entangled states". Physical Review Letters. 71 (11): 1665–1668. Bibcode:1993PhRvL..71.1665H. doi:10.1103/PhysRevLett.71.1665. PMID   10054467.
  8. Hardy, Lucien (2001-01-03). "Quantum Theory From Five Reasonable Axioms". arXiv: quant-ph/0101012 .
  9. Darrigol, Olivier (November 2015). "'Shut up and contemplate!': Lucien Hardy׳s reasonable axioms for quantum theory". Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics. 52, Part B: 328–342.