Researchers document a quantum spin wave for light

Phys.org August 19, 2019 Researchers at Purdue University have developed a unified perspective of unidirectional topological edge waves in nonreciprocal media. They focused on the inherent role of photonic spin in nonreciprocal gyroelectric media, i.e. magnetized metals or magnetized insulators. Hamiltonian approach predicts the existence of a third distinct class of Maxwellian edge wave exhibiting topological protection. This occurs in an intriguing topological bosonic phase of matter, fundamentally different from any known electronic or photonic medium. The goal of their paper is to discuss the three foundational classes of edge waves in a unified perspective while providing in-depth derivations, taking […]

Physicists find first possible 3-D quantum spin liquid

Phys.org  July 15, 2019 A quantum spin liquid is a state of matter where unpaired electrons’ spins, although entangled, do not show magnetic order even at the zero temperature. An international team of researchers (USA – Rice University, UC San Diego, Oak Ridge National Laboratory, Rutgers University, industry, UK, Switzerland, South Korea, University of Hong Kong) used thermodynamic, muon spin relaxation and neutron scattering experiments on single crystals of Ce2Zr2O7 to demonstrate the absence of magnetic ordering and the presence of a spin excitation continuum at 35 mK. With no evidence of oxygen deficiency and magnetic/non-magnetic ion disorder seen by neutron […]

Perfect quantum portal emerges at exotic interface

Nanowerk  June 26, 2019 A team of researchers in the US (University of Maryland, UC Irvine) has observed perfect Andreev reflection in point-contact spectroscopy—a clear signature of Klein tunneling and a manifestation of the underlying ‘relativistic’ physics of a proximity-induced superconducting state in a topological Kondo insulator. The findings shed light on a previously overlooked aspect of topological superconductivity and can serve as the basis for a unique family of spintronic and superconducting devices, the interface transport phenomena of which are completely governed by their helical topological states…read more. TECHNICAL ARTICLE  

Quantum physics experiment shows Heisenberg was right about uncertainty, in a certain sense

Phys.org  June 17, 2019 In a double slit experiment an international team of researchers (China, Australia, Sweden) reconstructed the hypothesised motion of the quantum particles, from many different possible starting points across both slits, and for both results of the measurement. They compared the velocities over time when there was no measurement device present to those when there was, and so determined the change in the velocities as a result of the measurement. The experiment showed that the effect of the measurement on the velocity of the particles continued long after the particles had cleared the measurement device itself, as […]

Physicists can predict the jumps of Schrodinger’s cat (and finally save it)

Phys.org  June 3, 2019 An international team of researchers (USA – Yale University, New Zealand) used a special approach to indirectly monitor a superconducting artificial atom, with three microwave generators irradiating the atom enclosed in a 3-D cavity made of aluminum. Microwave radiation stirs the artificial atom as it is simultaneously being observed, resulting in quantum jumps. They amplified the tiny quantum signal of these jumps and monitored it in real time which enabled the researchers to see a sudden absence of detection photons which was a warning of a quantum jump. Despite its observation, coherence increased during the jump. […]

Questions in quantum computing—how to move electrons with light

Phys.org  February 12, 2019 To study the light-matter interaction an international team of researchers (japan, Ukraine) coupled the cyclotron motion of a collection of electrons on the surface of liquid helium to the microwave field. For the corotating component of the microwave field, the strong coupling is pronouncedly manifested by the normal-mode splitting in the spectrum of coupled field-particle motion. For the counterrotating component of the microwave field, they observed a strong resonance when the microwave frequency is close to both the cyclotron and cavity frequencies. They found that fluctuations in the speed, location or overall charge of individual electrons […]

Quantum strangeness gives rise to new electronics

Eurekalert  February 11, 2019 An international team of researchers (USA – Arizona State University, Japan, China, UK) explored the charge transport properties through the molecules. They demonstrated that quantum interference can be precisely modulated in two different configurations of the molecule, known as Para and Meta. It turns out that quantum interference effects can cause substantial variation in the conductance properties of molecule-scale devices. By controlling the quantum interference, the group showed that electrical conductance of a single molecule can be fine-tuned over two orders of magnitude. The research shows that the field of molecular electronics is open to a […]

Current generation via quantum proton transfer

Nanowerk  January 23, 2019 Researchers in Japan have observed quantum tunneling effect in proton-transfer (PT) during potential-induced transformation of dioxygen on a platinum electrode in a low overpotential region at 298 K. This process is converted to the classical PT scheme in the high overpotential region. This observation indicates that the quantum tunneling governs the multistep electron-proton-driven transformation of dioxygen in the low overpotential condition. It shows the involvement of QTE in proton transfer during the basic energy conversion processes. The discovery may facilitate investigations of microscopic mechanisms of electrochemical reactions and stimulate the development of highly efficient electrochemical energy conversion […]

Honing quantum sensing

MIT News  September 25, 2018 Extreme sensitivity of quantum sensors to their surrounding environment creates the vexing problem of environmental noise in quantum sensor systems. A team of researchers in the US (MIT, Yale University) has developed an approach that is complementary to existing Dynamical decoupling and established error-corrected quantum sensing (ECQS) methods. This approach allows frequency-independent filtering, because it exploits spatial rather than temporal noise correlations. The new ECQS scheme makes use of noise correlations at different positions in a quantum sensor. In this way, the new approach can tell signal from noise even in the common case where […]

Searching for errors in the quantum world

Science Daily  September 18, 2018 Many scientists dream of combining quantum mechanics with the theory of relativity to form a coherent worldview. As actually experiments are not possible, researchers in Switzerland propose a thought experiment to investigate the question whether quantum theory can, in principle, have universal validity. The idea is that, if the answer was yes, it must be possible to employ quantum theory to model complex systems that include agents which are themselves using quantum theory. Analysing the experiment under this presumption, they found that one agent, upon observing a particular measurement outcome, must conclude that another agent […]