Can a solid be a superfluid? Engineering a novel supersolid state from layered 2D materials

Nanowerk  March 30, 2023 A supersolid a counterintuitive quantum state in which a rigid lattice of particles flows without resistance, has not been unambiguously realized. An international team of researchers (Belgium, Italy, Australia, Brazil) has revealed a supersolid ground state of excitons in a double-layer semiconductor heterostructure over a wide range of layer separations outside the focus of recent experiments. It conforms to the original Chester supersolid with one exciton per supersolid site, as distinct from the alternative version reported in cold-atom systems of a periodic density modulation or clustering of the superfluid. They provided the phase diagram augmented by […]

Scientists demonstrate quantum recoil for the first time, paving the way for precise X-ray imaging

Phys.org  January 19, 2023 More than 80 years after quantum recoil was proposed researchers in Singapore have demonstrated the phenomenon of quantum recoil showing that it is observable at room temperature. By scattering free electrons off the periodic two-dimensional atomic sheets of van der Waals materials in a tabletop platform, they showed that the X-ray photon energy is accurately predicted only by quantum recoil theory, that it can be enormous, to the point that a classically predicted X-ray photon is emitted as an extremely low-energy photon. According to the researchers quantum recoil is a means of precision control over outgoing […]

Antiferromagnets are suitable for transporting spin waves over long distances, study finds

Phys.org  December 6, 2022 In antiferromagnets, the efficient transport of spin-waves has until now only been observed in the insulating antiferromagnet hematite, where circularly polarized spin-waves diffuse over long distances. An international team of researchers (Germany, France, Norway, China) observed long-distance spin-transport in the antiferromagnetic orthoferrite YFeO3, where a different transport mechanism was enabled by the combined presence of the Dzyaloshinskii-Moriya interaction and externally applied fields. The magnon decay length exceeded hundreds of nanometers, in line with resonance measurements that highlight the low magnetic damping. They observed a strong anisotropy in the magnon decay lengths which they attributed to the […]

Direct printing of nanodiamonds at the quantum level

Nanowerk  May 4, 2022 The quantum defects in nanodiamonds, such as nitrogen-vacancy (NV) centers, are emerging as promising candidates for nanoscale sensing and imaging, and the controlled placement with respect to target locations is vital to their practical applications. Researchers in Hong Kong have developed on-demand electrohydrodynamic printing of nanodiamonds containing NV centers with high precision control over quantity and position. After thorough characterizations of the printing conditions, they showed that the number of printed nanodiamonds can be controlled at will, attaining the single-particle level precision. This printing approach enables positioning NV center arrays with a controlled number directly on […]

Zero-index metamaterials offer new insights into the foundations of quantum mechanics

Phys.org  April 27, 2022 Most theoretical derivations of fundamental radiative processes rely on energetic considerations and detailed balance equations, but not on momentum considerations. An international team of researchers (USA – Harvard University, University of Pennsylvania, Belgium, Spain, Denmark) re-examined the foundations of quantum physics from the perspective of momentum and explored what happens when the momentum of light is reduced to zero. They theoretically demonstrated that momentum recoil, transfer momentum from the field to the atom and Doppler shift are inhibited in NZI materials. Fundamental radiative processes inhibition is also explained due to those momentum considerations inside three-dimensional NZI […]

Discovery of matter-wave polaritons sheds new light on photonic quantum technologies

Phys.org  April 6, 2022 Exploiting the interaction between polaritons has led to the realization of superfluids of light as well as of strongly correlated phases in the microwave domain, with similar efforts underway for microcavity excitons–polaritons. Researchers at Stony Brook University have developed an ultracold-atom analogue of an exciton–polariton system in which interacting polaritonic phases can be studied with full tunability and in the absence of dissipation. In their optical lattice system, they replaced exciton by an atomic excitation, whereas an atomic matter wave was substituted for the photon under a strong dynamical coupling between the two constituents that hybridizes […]

Engineering the quantum states in solids using light

Science Daily  March 30, 2022 In previous experiments, the light intensity for realizing Floquet state (where the original quantum state is replicated when light is irradiated on matters) in solids was enormous due to the high frequency of light. An international team of researchers (South Korea, Japan) succeeded in the experimental realization of the steady Floquet state in a graphene Josephson junction (GJJ) by irradiating continuous microwaves on it. The intensity of the light was decreased to one trillionth the value of previous experiments, significantly reducing the heat generation and enabling continuously long-lasting Floquet states. They also developed a novel […]

Researchers Set Record by Preserving Quantum States in Silicon Carbide for More Than Five Seconds

SciTech  Daily March 13, 2022 Inability to easily read the information held in qubits, and the short coherence of qubits are impediments to the many technological applications of quantum science such as hacker proof communications networks and quantum computers. An international team of researchers (USA – University of Chicago, Argonne National Laboratory, Japan, Sweden) has demonstrated single-shot readout of single defects in SiC via spin-to-charge conversion, whereby the defect’s spin state was mapped onto a long-lived charge state. With this technique, they achieved over 80% readout fidelity without pre- or post-selection, resulting in a high signal-to-noise ratio that enabled them […]

Vacuum fluctuations break topological protection

Phys.org  March 4, 2022 The prospect of controlling the electronic properties of materials via the vacuum fields of cavity electromagnetic resonators is emerging as one of the frontiers of condensed matter physics. An international team of researchers (Switzerland, France) found that the enhancement of vacuum field fluctuations in subwavelength split-ring resonators strongly affects the quantum Hall electron transport in high-mobility two-dimensional electron gases. The observed breakdown of the topological protection of the integer quantum Hall effect is interpreted in terms of a long-range cavity-mediated electron hopping where the anti-resonant terms of the light-matter coupling develop into a finite resistivity induced […]

First observation of the quantum boomerang effect

Nanowerk  February 28, 2022 The boomerang effect is a disorder-induced behavior which inhibits transport of electrons turning what would otherwise be a conducting material into an insulator. An international team of researchers (USA – UC Santa Barbara, Brazil, France) reported experimental observation and characterization of this surprising quantum-mechanical phenomenon. They exposed a gas of ultracold lithium atoms to a phase-shifted pair of optical lattices to realize a “quantum kicked rotor,” a momentum-space realization of Anderson-localized matter. They observed the characteristic departure from and return to the origin that is the key signature of the boomerang effect. Detailed characterization revealed the […]