D-Wave opens up access to its next-generation 500 qubit quantum computer Advantage2.
Category: quantum physics – Page 594
Quantum nature of hydrogen bonds observed in acid–base complex
Researchers in the US have demonstrated the presence of quantum mechanical effects in acid–base interactions, challenging the Brønsted–Lowry theory. The resultant short hydrogen bond is stabilised by a delocalised proton, which rapidly shuttles between the acid and base molecules and is characterised by highly unusual spectral features.
The Brønsted–Lowry theory was proposed in 1923 and explains acid–base interactions in terms of proton transfer. This theory is one of the cornerstones of chemical understanding and is amongst the first principles taught to school students. But despite a growing appreciation for the limitations of traditional thinking, the surprising discovery of a quantum component to such fundamental reactivity was entirely serendipitous.
‘It was luck,’ admits Daniel Kuroda of Louisiana State University, one of the principal researchers involved in the study. ‘We were looking at the structure of liquids … and saw this paper [about an acid–base mixture] with close to the conductivity of sulfuric acid but no ionisation. We wanted to see what the structure was … so we started looking into the project and then realised that clearly we have something very different.’
Quantum electrodynamics tested 100 times more accurately than ever
Using a newly developed technique, scientists at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg have measured the very small difference in the magnetic properties of two isotopes of highly charged neon in an ion trap with previously inaccessible accuracy. Comparison with equally extremely precise theoretical calculations of this difference allows a record-level test of quantum electrodynamics (QED). The agreement of the results is an impressive confirmation of the standard model of physics, allowing conclusions regarding the properties of nuclei and setting limits for new physics and dark matter.
Electrons are some of the most fundamental building blocks of the matter we know. They are characterized by some very distinctive properties, such as their negative charge and the existence of a very specific intrinsic angular momentum, also called spin. As a charged particle with spin, each electron has a magnetic moment that aligns itself in a magnetic field similar to a compass needle. The strength of this magnetic moment, given by the so-called g-factor, can be predicted with extraordinary accuracy by quantum electrodynamics. This calculation agrees with the experimentally measured g-factor to within 12 digits, one of the most precise matches of theory and experiment in physics to date. However, the magnetic moment of the electron changes as soon as it is no longer a “free” particle, i.e., unaffected by other influences, but instead is bound to an atomic nucleus, for example.
Physicists make leaps in reading out qubits with laser light
Qubits are a basic building block for quantum computers, but they’re also notoriously fragile—tricky to observe without erasing their information in the process. Now, new research from the University of Colorado Boulder and the National Institute of Standards and Technology (NIST) could be a leap forward for handling qubits with a light touch.
In the study, a team of physicists demonstrated that it could read out the signals from a type of qubit called a superconducting qubit using laser light, and without destroying the qubit at the same time.
The group’s results could be a major step toward building a quantum internet, the researchers say. Such a network would link up dozens or even hundreds of quantum chips, allowing engineers to solve problems that are beyond the reach of even the fastest supercomputers around today. They could also, theoretically, use a similar set of tools to send unbreakable codes over long distances.
Harnessing machine learning to analyze quantum material
Electrons and their behavior pose fascinating questions for quantum physicists, and recent innovations in sources, instruments and facilities allow researchers to potentially access even more of the information encoded in quantum materials.
However, these research innovations are producing unprecedented—and until now, indecipherable—volumes of data.
“The information content in a piece of material can quickly exceed the total information content in the Library of Congress, which is about 20 terabytes,” said Eun-Ah Kim, professor of physics in the College of Arts and Sciences, who is at the forefront of both quantum materials research and harnessing the power of machine learning to analyze data from quantum material experiments.
Physicists build an atom laser that can stay on forever
Lasers produce coherent waves of light: All the light inside a laser vibrates completely in sync. Meanwhile, quantum mechanics tells us that particles like atoms should also be thought of as waves. As a result, we can build “atom lasers” containing coherent waves of matter. But can we make these matter waves last, so that they may be used in applications? In research that was published in Nature this week, a team of Amsterdam physicists shows that the answer to this question is affirmative.
Getting bosons to march in sync
The concept that underlies the atom laser is the so-called Bose-Einstein Condensate, or BEC for short. Elementary particles in nature occur in two types: fermions and bosons. Fermions are particles like electrons and quarks—the building blocks of the matter that we are made of. Bosons are very different in nature: they are not hard like fermions, but soft: for example, they can move through one another without a problem. The best-known example of a boson is the photon, the smallest possible quantity of light. But matter particles can also combine to form bosons—in fact, entire atoms can behave just like particles of light. What makes bosons so special is that they can all be in the exact same state at the exact same time, or phrased in more technical terms, they can “condense” into a coherent wave. When this type of condensation happens for matter particles, physicists call the resulting substance a Bose-Einstein Condensate.
Grand Unification as a Bridge Between String Theory And Phenomenology
Circa 2006 string theory would explain everything even extradimensional beings or even weird phenomenon. Basically it could even explain something even greater about our existence that even a God level entity had a grand design of our universe. It could even explain miracles by these entities using string theory. Even Einstein thought that there could be a great designer and oddly enough this could explain all things in physics and our world even an infinite multiverse that our universe is much more odd then we previously thought. String theory could even essentially be the next step after quantum mechanics.
In the first part of this paper, we explain what empirical evidence points to the need for having an effective grand unification-like symmetry possessing the symmetry SU-color in 4D. If one assumes the premises of a future predictive theory including gravity — be it string/M-theory or a reincarnation — this evidence then suggests that such a theory should lead to an effective grand unification-like symmetry as above in 4D, near the string-GUT-scale, rather than the standard model symmetry. Advantages of an effective supersymmetric G(224) = SU L × SU R × SU c or SO(10) symmetry in 4D in explaining (i) observed neutrino oscillations, (ii) baryogenesis via leptogenesis, and (iii) certain fermion mass-relations are noted. And certain distinguishing tests of a SUSY G(224) or SO(10)-framework involving CP and flavor violations (as in μ → eγ, τ → μγ, edm’s of the neutron and the electron) as well as proton decay are briefly mentioned.
Recalling some of the successes we have had in our understanding of nature so far, and the current difficulties of string/M-theory as regards the large multiplicity of string vacua, some comments are made on the traditional goal of understanding vis a vis the recently evolved view of landscape and anthropism.
Invited plenary talk delivered at the International Conference on Einstein’s Legacy in the New Millennium, December 15–22, 2005, Puri, India.