Scientists led by the University of Massachusetts Amherst have adapted a device called a microwave circulator for use in quantum computers, allowing them for the first time to precisely tune the exact degree of nonreciprocity ...
Quantum Physics
15 hours ago
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76
Radiation from space is a challenge for quantum computers as their computation time becomes limited by cosmic rays. Researchers from Chalmers University of Technology, Sweden, and University of Waterloo in Canada are now ...
Quantum Physics
Apr 29, 2024
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26
In a new study published inNature Physics, scientists at the MAJORANA Collaboration have tested the stringency of charge conservation and Pauli's exclusion principles using underground detectors. Alessio Porcelli has published ...
Researchers at the University of Copenhagen's Niels Bohr Institute have developed a new way to create quantum memory: A small drum can store data sent with light in its sonic vibrations, and then forward the data with new ...
Optics & Photonics
Apr 15, 2024
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212
Rice University physicists have discovered a phase-changing quantum material—and a method for finding more like it—that could potentially be used to create flash-like memory capable of storing quantum bits of information, ...
General Physics
Apr 6, 2024
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400
Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons ...
Nanomaterials
Apr 3, 2024
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124
Exploring cavity quantum electrodynamics (cQED) is pivotal for advancing quantum technology and unraveling the fundamental intricacies of light-matter interactions. A prevalent strategy involves integrating a single quantum ...
Optics & Photonics
Apr 2, 2024
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17
Researchers at DTU have successfully distributed a quantum-secure key using a method called continuous variable quantum key distribution (CV QKD). The researchers have managed to make the method work over a record 100 km ...
Quantum Physics
Apr 2, 2024
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108
Ever since its discovery, dark matter has remained invisible to scientists despite the launch of multiple ultra-sensitive particle detector experiments around the world over several decades.
General Physics
Mar 27, 2024
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128
U.S. Naval Research Laboratory (NRL) scientists have published the Cascaded Variational Quantum Eigensolver (CVQE) algorithm in a recent Physical Review Research article. The algorithm is expected to become a powerful tool ...
Quantum Physics
Mar 25, 2024
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527
In quantum physics, a quantum state is a mathematical object that fully describes a quantum system. One typically imagines some experimental apparatus and procedure which "prepares" this quantum state; the mathematical object then reflects the setup of the apparatus. Quantum states can be statistically mixed, corresponding to an experiment involving a random change of the parameters. States obtained in this way are called mixed states, as opposed to pure states, which cannot be described as a mixture of others. When performing a certain measurement on a quantum state, the result generally described by a probability distribution, and the form that this distribution takes is completely determined by the quantum state and the observable describing the measurement. However, unlike in classical mechanics, the result of a measurement on even a pure quantum state is only determined probabilistically. This reflects a core difference between classical and quantum physics.
Mathematically, a pure quantum state is typically represented by a vector in a Hilbert space. In physics, bra-ket notation is often used to denote such vectors. Linear combinations (superpositions) of vectors can describe interference phenomena. Mixed quantum states are described by density matrices.
In a more general mathematical context, quantum states can be understood as positive normalized linear functionals on a C* algebra; see GNS construction.
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