Chinese researchers achieved the first loophole-free test of Hardy’s paradox, providing compelling evidence of quantum nonlocality and advancing quantum technology development.
A research team from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), led by Prof. Jianwei Pan, Qiang Zhang, and Kai Chen, in collaboration with CHEN Jingling from Nankai University, has achieved the loophole-free test of Hardy’s paradox for the first time. The team successfully demonstrated Hardy’s nonlocality, closing both the detection efficiency loophole and the locality loophole. Their findings were published in Physical Review Letters as an Editor’s Suggestion.
Hardy’s paradox, introduced by Lucien Hardy in the 1990s, offers a simplified test of local realism—the classical idea that physical properties exist independently of observation and that no signals exceed the speed of light. This paradox exposes the conflict between quantum mechanics and local realism by demonstrating that, under certain conditions where three “Hardy events” have a zero probability, quantum mechanics predicts a non-zero probability for a fourth event, which contradicts local realism.
Challenges of Testing Hardy’s Paradox
Experimentally confirming Hardy’s paradox is challenging due to the low probability of the fourth event, requiring high fidelity and efficiency in entanglement sources to distinguish it from noise. Prior experiments faced two main challenges: the locality loophole, where measurement choices could affect outcomes, and the detection efficiency loophole, due to optical losses.
In addressing the locality loophole, the researchers meticulously crafted a space-time experimental setup that ensured the measurement choices were spacelike separated from both the entangled state preparations and the photon detections. This configuration precludes any possibility of the measurement settings being influenced by the outcomes, thereby eliminating the locality loophole.
Addressing the Locality and Detection Efficiency Loopholes
To tackle the detection efficiency loophole, the study employed a high detection efficiency of 82.2%, which substantially mitigates the impact of optical losses. Moreover, the integration of high-speed quantum random number generators for the selection of measurement settings introduced an element of true randomness, safeguarding against any potential manipulation by local hidden variables. By also incorporating undetected events and double-click events into their analysis through a refined form of Hardy’s inequality, the researchers effectively closed the detection efficiency loophole, presenting a robust experimental framework that stands as a significant contribution to the field of quantum physics.
Finally, the experiment, conducted over six hours, demonstrated a strong violation of Hardy’s paradox, with a significance level of up to 5 standard deviations across 4.32 billion trials. A null hypothesis test confirmed that the probability of explaining the results through local realism is less than 10-16348, providing compelling evidence in favor of quantum nonlocality.
This research deepens our understanding of quantum mechanics and has significant implications for developing quantum technologies such as quantum key distribution and quantum random number certification. It marks an advancement in quantum physics, offering new evidence of quantum nonlocality and paving the way for future quantum information technologies. The referees of the study highly praised the work, noting that “the experimental results, along with the quantified evidence against local realism, are impressive.”
Reference: “Loophole-Free Test of Local Realism via Hardy’s Violation” by Si-Ran Zhao, Shuai Zhao, Hai-Hao Dong, Wen-Zhao Liu, Jing-Ling Chen, Kai Chen, Qiang Zhang and Jian-Wei Pan, 7 August 2024, Physical Review Letters.
DOI: 10.1103/PhysRevLett.133.060201
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18 Comments
Hardy’s paradox, introduced by Lucien Hardy in the 1990s, offers a simplified test of local realism—the classical idea that physical properties exist independently of observation and that no signals exceed the speed of light.
Ask the researchers:
1. What are the similarities and differences between the observed speed of light in physics experiments and the Relativistic speed of light?
2. Is Physical Review Letters a trustworthy publication?
When physics is passionate about studying imaginary particles and things, it is no longer much different from theology.
Scientific research guided by correct theories can help people avoid detours, failures, and exaggeration. The physical phenomena observed by researchers in experiments are always appearances, never the natural essence of things. The natural essence of things needs to be extracted and sublimated based on mathematical theories via appearances , rather than being imagined arbitrarily.
Everytime scientific revolution, the scientific research space brought by the new paradigm expands exponentially. Physics should not ignore the analyzable physical properties of topological vortices.
(1) Traditional physics: based on mathematical formalism, experimental verification and arbitrary imagination.
(2) Topological Vortex Theory: Although also based on mathematics (such as topology), it focuses more on non intuitive geometry and topological structures, challenging traditional physical intuition.
Topological Vortex Theory points out the limitations of the Standard Model in describing the large-scale structure of the universe, proposes the need to consider non-standard model components such as dark matter and dark energy, and suggests that topological vortex fields may be key to understanding these phenomena. Topological vortex theory heralds innovative technologies such as topological electronics, topological smart batteries, topological quantum computing, etc., which may bring low-energy electronic components, almost inexhaustible currents, and revolutionary computing platforms, etc.
Topology tells us that topological vortices and antivortices can form new spacetime structures via the synchronous effect of superposition, deflection, or twisting of them. Mathematics does not tell us that there must be God particles, ghost particles, fermions, or bosons present. When physics and mathematics diverge, arbitrary imagination will make physics no different from theology. Topological vortex research reflections on the philosophy and methodology of science help us understand the nature essence of science and the limitations of scientific methods. This not only has guiding significance for scientific research itself, but also has important implications for science education and popularization.
Today, so-called official (such as PRL, Nature, Science, PNAS, etc.) in physics stubbornly believes that two sets of cobalt-60 rotating in opposite directions can become two sets of objects that mirror each other, is a typical case that pseudoscience is rampant and domineering.
Please witness the exemplary collaboration between theoretical physicists and experimentalists (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286). Let us continue to witness together the dirtiest and ugliest era in the scientific and humanistic history of human society. The laws of nature will not change due to misleading of certain so-called academic publications or endorsements from certain so-called scientific awards.
Hardy’s paradox indeed highlights the tension between quantum mechanics and local realism. The recent experiment addressed significant challenges, such as the locality and detection efficiency loopholes, providing robust evidence against local realism and in favor of quantum nonlocality.
On the Speed of Light in Relativity vs. Experiment: Relativity posits that the speed of light in a vacuum is constant. Experiments consistently confirm this, and Hardy’s paradox doesn’t alter or dispute this fact; instead, it explores quantum entanglement’s implications for local realism, unrelated to relativity’s speed constraints.
Validity of Physical Review Letters (PRL): PRL is a highly respected, peer-reviewed journal known for rigorous standards and substantial contributions to physics. Questioning its credibility without specific, substantiated evidence is unwarranted. The PRL reviewers praised this experiment for its robust statistical validity and methodological precision.
Quantum Physics vs. Theology: While quantum mechanics delves into non-intuitive phenomena, equating it with theology is overly reductive. Unlike theology, physics—no matter how abstract—relies on empirical testing and falsifiability, as evidenced by the extensive data underpinning this experiment’s findings.
Topological Vortex Theory (TVT) and the Standard Model: TVT may indeed offer new perspectives, particularly in abstract geometry. However, its current lack of experimental validation distinguishes it from models like the Standard Model, which has broad empirical support. Calling for more focus on TVT’s ideas is valid, but it shouldn’t dismiss rigorously tested theories like those underpinning the Standard Model.
Physics Journals and Allegations of Pseudoscience: Scientific journals uphold standards that demand peer review, replication, and correction when errors are found. Broadly dismissing journals as pseudoscientific due to select disagreements undermines this scientific rigor and contributes little to constructive debate.
The achievements of this experiment advance our understanding of quantum mechanics and strengthen the empirical basis of quantum nonlocality, marking significant progress in a foundational area of modern physics.
On the Speed of Light in Relativity vs. Experiment. The physical essence of the speed of light in relativity is synchronization. Is there any speed faster than synchronization in nature? How do you observe synchronous effects in scientific experiments? Is scientific experimentation omnipotent?
Validity of Physical Review Letters (PRL). PRL stubbornly believes that two sets of cobalt-60 rotating in opposite directions can become two sets of objects that mirror each other, is it scientific and rigorous?
Quantum Physics vs. Theology. When physics is passionate about studying imaginary particles and things, it is no longer much different from theology. Why would one rather use a cat that is both dead and alive as an analogy to quantum than a topological structure in nature?
Topological Vortex Theory (TVT) and the Standard Model. Topological Vortex Theory points out the limitations of the Standard Model in describing the large-scale structure of the universe. Topological vortex research reflections on the philosophy and methodology of science help us understand the nature essence of science and the limitations of scientific methods. This not only has guiding significance for scientific research itself, but also has important implications for science education and popularization.
Physics Journals and Allegations of Pseudoscience. Some so-called scholars and academic publications blatantly talk nonsense and hardly know what shame is. If you have patience or truly love science, please witness the exemplary collaboration between theoretical physicists and experimentalists (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286).
The notions here are off topic from the published work that is discussed. There is no published “topological vortex theory”, say.
The only pertinent question is about the scientific journal.
“Physical Review Letters (PRL), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. The journal is considered one of the most prestigious in the field of physics. Over a quarter of Physics Nobel Prize-winning papers between 1995 and 2017 were published in it.” [Wikipedia]
“The notions here are off topic…”
Solid evidence you’re talking to yourself too much here, “Larsson.”
@Torbjörn Larsson.
1. PRL stubbornly believes that two sets of cobalt-60 rotating in opposite directions can become two sets of objects that mirror each other, is it scientific and rigorous?
2. Does PRL and its family of publications have no responsibility to clarify the fallacies of PR in the past?
If you have patience or truly love science, please witness the exemplary collaboration between theoretical physicists and experimentalists (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286).
Ask Torbjörn Larsson.
Does PRL and its family of publications have no responsibility to clarify the fallacies of PR in the past?
Ask Torbjörn Larsson again.
1. Has the Nobel Prize never been awarded to pseudoscience?
2. How do you confirm the scientific validity of the Nobel Prize?
3. Is peer review necessarily scientific?
Summary of all multi-slit experiments:
1.) Going nowhere, usually at an amazing rate.
2.) Perfect trick to hide invisible things.
3.) Peerless excuse to scientifically bring up Einstein “God” and “spooky.”
Despite being simpler in spirit, the paper notes that the Hardy version was beaten by ordinary Bell test experiments in closing these loopholes.
That joint probabilities of quantum field observations (here QED physics) from different reference frames may not add linearly is no odder than that other relativistic measurements may not preserve times or lengths for different observers. What is immutably “real” is the laws, not the frame dependent observations.
Oops. Disregard the misplaced longer comment, it was a response to the article.
The work here confirms Bell test experiments, so it is going somewhere despite any empty trolling to the opposite.
“empty trolling”
Empty trolling is You claiming entanglement with quasars has been accomplished, over at phys-org a few years ago, then running away because the claim is indefensible.
You and your asinine obnoxious slaking avatar always waiting a few days to respond and never following up with anything. I keep telling you to stop replying to me and you keep ignoring that and running away. You’re a political propaganda clown, only explanation.
I suppose bored trolls will claw their way up to any part of the Internet — even SciTechDaily.
Begone, troll! Return to the muck from whence you came. Shoo!
Bangers, Shoo Pest. We owe you a tall cold one.
Despite being simpler in spirit, the paper notes that the Hardy version was beaten by ordinary Bell test experiments in closing these loopholes.
That joint probabilities of quantum field observations (here QED physics) from different reference frames may not add linearly is no odder than that other relativistic measurements may not preserve times or lengths for different observers. What is immutably “real” is the laws, not the frame dependent observations.
Whatever the meaning assigned to the term complete, the following requirement for a complete theory seems to be a necessary one: every element of the physical reality must have a counterpart in the physical theory.
~EPR
If you ask a physicist what is his idea of yellow light, he will tell you that it is transversal electromagnetic waves of wavelength in the neighborhood of 590 millimicrons. If you ask him: But where does yellow come in? he will say: In my picture not at all, but these kinds of vibrations, when they hit the retina of a healthy eye, give the person whose eye it is the sensation of yellow.
~Schrödinger
The characteristic of an n-dimensional manifold is that each of the elements composing it (in our examples, single points, […] colors, tones) may be specified by the giving of n quantities, the “co-ordinates,” which are continuous functions within the manifold.
~Weyl
So few and far between are the occasions for forming notions whose specializations make up a continuous manifold, that the only simple notions whose specializations form a multiply extended manifold are the positions of perceived objects and colors. More frequent occasions for the creation and development of these notions occur first in higher mathematics.
~Riemann
What we see depends on light entering the eye. Furthermore, we do not even perceive what enters the eye. The things transmitted are waves or — as Newton thought — minute particles, and the things seen are colors. Locke met this difficulty by a theory of primary and secondary qualities. Namely, there are some attributes of the matter which we do perceive. These are the primary qualities, and there are other things which we perceive, such as colors, which are not attributes of matter, but are perceived by us as if they were such attributes. These are the secondary qualities of matter.
Why should we perceive secondary qualities? It seems an unfortunate arrangement that we should perceive a lot of things that are not there.
~Whitehead
Light does not ‘travel’, it energizes at different rates, depending on frequency, and therefore ‘distance’ must be eliminated from light, and until mankind can do this, and a density table of light developed, all he/she theorizes is nonsense.