Using the valley degree of freedom in analogy to spin to encode qubits could be advantageous as many of the known decoherence mechanisms do not apply. Now long relaxation times are demonstrated for valley qubits in bilayer graphene quantum dots.
Category: quantum physics – Page 273
An international team of researchers from Leibniz University Hannover (Germany) and the University of Strathclyde in Glasgow (United Kingdom) has disproved a previously held assumption about the impact of multiphoton components in interference effects of thermal fields (e.g., sunlight) and parametric single photons (generated in non-linear crystals). The journal Physical Review Letters has published the team’s research.
“We experimentally proved that the interference effect between thermal light and parametric single photons also leads to quantum interference with the background field. For this reason, the background cannot simply be neglected and subtracted from calculations, as has been the case up to now,” says Prof. Dr. Michael Kues, Head of the Institute of Photonics and member of the Board of the PhoenixD Cluster of Excellence at Leibniz University Hannover.
The leading scientist was Ph.D. student Anahita Khodadad Kashi, who performs research on photonic quantum information processing at the Institute of Photonics. She investigated how the visibility of the so-called Hong-Ou-Mandel effect, a quantum interference effect, is affected by multiphoton contamination.
Language models offer promises in encoding quantum correlations and learning complex quantum states. This Perspective discusses the advantages of employing language models in quantum simulation, explores recent model developments, and offers insights into opportunities for realizing scalable and accurate quantum simulation.
Researchers at HZB have created an innovative technique to precisely measure minuscule temperature variations as small as 100 microkelvin in the thermal Hall effect, overcoming previous limitations caused by thermal noise. By applying this technique to terbium titanate, the team showcased its effectiveness in producing consistent and dependable outcomes. This advancement in measuring the thermal Hall effect sheds light on the behavior of coherent multi-particle states in quantum materials, particularly their interactions with lattice vibrations, known as phonons.
The laws of quantum physics apply to all materials. However, in so-called quantum materials, these laws give rise to particularly unusual properties. For example, magnetic fields or changes in temperature can cause excitations, collective states, or quasiparticles that are accompanied by phase transitions to exotic states. This can be utilised in a variety of ways, provided it can be understood, managed, and controlled: For example, in future information technologies that can store or process data with minimal energy requirements.
The thermal Hall effect (THE) plays a key role in identifying exotic states in condensed matter. The effect is based on tiny transverse temperature differences that occur when a thermal current is passed through a sample and a perpendicular magnetic field is applied (see Figure 2). In particular, the quantitative measurement of the thermal Hall effect allows us to separate the exotic excitations from conventional behavior.
With anaesthetics and brain organoids, we are finally testing whether quantum effects can explain consciousness. We may have misunderstood this long-derided idea, says George Musser.
By Chuck Brooks
Computing paradigms as we know them will exponentially change when artificial intelligence is combined with classical, biological, chemical, and quantum computing. Artificial intelligence might guide and enhance quantum computing, run in a 5G or 6G environment, facilitate the Internet of Things, and stimulate materials science, biotech, genomics, and the metaverse.
Computers that can execute more than a quadrillion calculations per second should be available within the next ten years. We will also rely on clever computing software solutions to automate knowledge labor. Artificial intelligence technologies that improve cognitive performance across all envisioned industry verticals will support our future computing.
Advanced computing has a fascinating and mind-blowing future. It will include computers that can communicate via lightwave transmission, function as a human-machine interface, and self-assemble and teach themselves thanks to artificial intelligence. One day, computers might have sentience.
PRESS RELEASE — It is hard to imagine our lives without networks such as the internet or mobile phone networks. In the future, similar networks are planned for quantum technologies that will enable the tap-proof transmission of messages using quantum cryptography and make it possible to connect quantum computers to each other.
Like their conventional counterparts, such quantum networks require memory elements in which information can be temporarily stored and routed as needed. A team of researchers at the University of Basel led by Professor Philipp Treutlein has now developed such a memory element, which can be micro-fabricated and is, therefore, suitable for mass production. Their results were recently published in the scientific journal Physical Review Letters.
An experiment conducted in Italy, with theory support from Newcastle University, has produced the first experimental evidence of vacuum decay.
In quantum field theory, when a not-so-stable state transforms into the true stable state, it’s called “false vacuum decay.” This happens through the creation of small localized bubbles. While existing theoretical work can predict how often this bubble formation occurs, there hasn’t been much experimental evidence.
Now, an international research team involving Newcastle University scientists has for the first observed these bubbles forming in carefully controlled atomic systems. Published in the journal Nature Physics, the findings offer experimental evidence of bubble formation through false vacuum decay in a quantum system.
A team of scientists at the Max Planck Institute for the Science of Light led by Dr. Birgit Stiller has succeeded in cooling traveling sound waves in waveguides considerably further than has previously been possible using laser light. This achievement represents a significant move towards the ultimate goal of reaching the quantum ground state of sound in waveguides.
Unwanted noise generated by the acoustic waves at room temperature can be eliminated. This experimental approach both provides a deeper understanding of the transition from classical to quantum phenomena of sound and is relevant to quantum communication systems and future quantum technologies.
The quantum ground state of an acoustic wave of a certain frequency can be reached by completely cooling the system. In this way, the number of quantum particles, the so-called acoustic phonons, which cause disturbance to quantum measurements, can be reduced to almost zero and the gap between classical and quantum mechanics bridged.
Photonic integrated circuits have grown as potential hardware for neural networks and quantum computing, yet the tuning speed and large power consumption limited the application. Here, authors introduce the memresonator, a memristor heterogeneously integrated with a microring resonator, as a non-volatile silicon photonic phase shifter to address these limitations.