Physicists are trying to rewrite the axioms of quantum theory from scratch in an effort to understand what it all means. The problem? They’ve been almost too successful.
Category: quantum physics – Page 694
Abstract: In this review-article, we discuss the consequences of the introduction of a quantum of time tau_0 in the formalism of non-relativistic quantum mechanics (QM) by referring ourselves in particular to the theory of the “chronon” as proposed by P.Caldirola. Such an interesting “finite difference” theory, forwards —at the classical level— a solution for the motion of a particle endowed with a non-negligible charge in an external electromagnetic field, overcoming all the known difficulties met by Abraham-Lorentz’s and Dirac’s approaches (and even allowing a clear answer to the question whether a free falling charged particle does or does not emit radiation), and —at the quantum level— yields a remarkable mass spectrum for leptons. After having briefly reviewed Caldirola’s approach, we compare one another the new Schroedinger, Heisenberg and density-operator (Liouville-von Neumann) pictures resulting from it. Moreover, for each representation, three (retarded, symmetric and advanced) formulations are possible, which refer either to times t and t-tau_0, or to times t-tau_0/2 and t+tau_0/2, or to times t and t+tau_0, respectively. It is interesting to notice that, e.g., the “retarded” QM does naturally appear to describe QM with friction, i.e., to describe dissipative quantum systems (like a particle moving in an absorbing medium). In this sense, discretized QM is much richer than the ordinary one. When the density matrix formalism is applied to the solution of the measurement problem in QM, very interesting results are met, so as a natural explication of “decoherence”.
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PDF | The introduction of quantum of time, called Chronon, and its consequences for the electron in quantum and classical physics is presented. The most impressive achievement related to the introduction of the chronon hypothesis in the realm of QM comes from the description of a…
An exotic physical phenomenon, involving optical waves, synthetic magnetic fields, and time reversal, has been directly observed for the first time, following decades of attempts. The new finding could lead to realizations of what are known as topological phases, and eventually to advances toward fault-tolerant quantum computers, the researchers say.
The new finding involves the non-Abelian Aharonov-Bohm Effect and is published in the journal Science by MIT graduate student Yi Yang, MIT visiting scholar Chao Peng (a professor at Peking University), MIT graduate student Di Zhu, Professor Hrvoje Buljan at University of Zagreb in Croatia, Francis Wright Davis Professor of Physics John Joannopoulos at MIT, Professor Bo Zhen at the University of Pennsylvania, and MIT professor of physics Marin Soljačić.
The finding relates to gauge fields, which describe transformations that particles undergo. Gauge fields fall into two classes, known as Abelian and non-Abelian. The Aharonov-Bohm Effect, named after the theorists who predicted it in 1959, confirmed that gauge fields — beyond being a pure mathematical aid — have physical consequences.
A talk by Dave Bacon during the Industry session of the 14th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2019), Day 3. TQC 2019 was hosted June 3–5, 2019 by the Joint Center for Quantum Information and Computer Science at the University of Maryland (QuICS). More information about TQC can be found at https://www.tqcconference.org.
Quantum many-body systems (QMBs), which are physical systems made up of multiple interacting particles, are among the most challenging structures to reproduce in numerical simulations. In the past, researchers have attempted to simulate these systems using a variety of techniques, including Monte Carlo simulations and even exact diagonalizations.
Methods involving tensor networks (TNs), mathematical concepts that can be applied in a variety of scientific fields, have also shown some potential for the simulation of QMBs. However, so far, these techniques have only been successfully applied to small systems or those with a simple geometry.
In a recent study, researchers at the University of Central Florida were able to simulate QMBs on Amazon Web Services using a TN-based method. Their paper, pre-published on arXiv, highlights some of the potential advantages and implications of using cloud services for research purposes.
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Quantum computing promises to revolutionize the ways in which scientists can process and manipulate information. The physical and material underpinnings for quantum technologies are still being explored, and researchers continue to look for new ways in which information can be manipulated and exchanged at the quantum level.
Our team is committed to making quantum sciences more approachable by investing heavily in the education to support this growing community and establishing the emerging technology as the next generation of computing. We need more students, educators, developers, and domain experts with “quantum ready” skills. This is why our team is proud to release educational resources and tools, while also increasing the capacity and capability of our IBM Q systems.
We are rolling out new systems and a new feature that allows for reserving time on an IBM Q system through the IBM Q Experience. This will initially be available to members of the IBM Q Network. Members will be able to reserve blocks of uninterrupted time for their users to experiment and test ideas using our advanced systems and software. Moreover, educators and academic members can take advantage of scheduling time to dynamically demonstrate quantum computing concepts on our hardware in the classroom. All the while, students can use the IBM Q Experience to follow along directly from a web browser without any additional installation required.
We published an open-source online textbook, called Learn Quantum Computation Using Qiskit, as a tool for self-learners and educators preparing the next generation of quantum developers. Written by experienced educators and leading researchers in the field, this textbook explores quantum computing through practical problems that are run on both simulators and real quantum hardware, with the aim of helping students connect theory to practice. And most importantly, because this textbook is open-source, the field’s top educators and contributors will continually update this text to ensure that students learn the latest and most-relevant quantum computing skills. The textbook also includes problem sets that can be included in coursework. Professors interested in the solutions to these problem sets should contact me – Abraham Asfaw. Additional information about the structure of the textbook can be found here.
When practical quantum computing finally arrives, it will have the power to crack the standard digital codes that safeguard online privacy and security for governments, corporations, and virtually everyone who uses the Internet. That’s why a U.S. government agency has challenged researchers to develop a new generation of quantum-resistant cryptographic algorithms.
Many experts don ’t expect a quantum computer capable of performing the complex calculations required to crack modern cryptography standards to become a reality within the next 10 years. But the U.S. National Institute of Standards and Technology (NIST) wants to stay ahead by getting new cryptographic standards ready by 2022. The agency is overseeing the second phase of its Post-Quantum Cryptography Standardization Process to narrow down the best candidates for quantum-resistant algorithms that can replace modern cryptography.
“Currently intractable computational problems that protect widely-deployed cryptosystems, such as RSA and Elliptic Curve-based schemes, are expected to become solvable,” says Rafael Misoczki, a cryptographer at the Intel Corporation and a member of two teams (named Bike and Classic McEliece) involved in the NIST process. “This means that quantum computers have the potential to eventually break most secure communications on the planet.”