Imagine you sit down and pick up your favourite book. You look at the image on the front cover, run your fingers across the smooth book sleeve, and smell that familiar book smell as you flick through the pages. To you, the book is made up of a range of sensory appearances.
Effective methods for decoupling superconducting qubits (SQs) from parasitic environmental noise sources are critical for increasing their lifetime and phase fidelity. While considerable progress has been made in this area, the microscopic origin of noise remains largely unknown. In this work, first principles density functional theory calculations are employed to identify the microscopic origins of magnetic noise sources in SQs on an α-Al_{2}O_{3} substrate. The results indicate that it is unlikely that the existence of intrinsic point defects and defect complexes in the substrate are responsible for low frequency noise in these systems. Rather, a comprehensive analysis of extrinsic defects shows that surface aluminum ions interacting with ambient molecules will form a bath of magnetic moments that can couple to the SQ paramagnetically. The microscopic origin of this magnetic noise source is discussed and strategies for ameliorating the effects of these magnetic defects are proposed.
PDF | Condensed matter systems act as mini-universes with emergent low-energy properties drastically different from those of the standard model. A case… | Find, read and cite all the research you need on ResearchGate.
Researchers have discovered a complex landscape of electronic states that can co-exist on a kagome lattice, resembling those in high-temperature superconductors, a team of Boston College physicists reports in an advance electronic publication of the journal Nature.
The focus of the study was a bulk single crystal of a topological kagome metal, known as CsV3Sb5—a metal that becomes superconducting below 2.5 degrees Kelvin, or minus 455 degrees Fahrenheit. The exotic material is built from atomic planes composed of Vanadium atoms arranged on a so-called kagome lattice—described as a pattern of interlaced triangles and hexagons—stacked on top of one another, with Cesium and Antimony spacer layers between the kagome planes.
The material offers a window into how the physical properties of quantum solids—such as light transmission, electrical conduction, or response to a magnetic field —relate to the underlying geometry of the atomic lattice structure. Because its geometry causes destructive interference and “frustrates” the kinetic motion of traversing electrons, kagome lattice materials are prized for offering the unique and fertile ground for the study of quantum electronic states described as frustrated, correlated and topological.
Nonlinearity induced by a single photon is desirable because it can drive power consumption of optical devices to their fundamental quantum limit, and is demonstrated here at room temperature.
The recent progress in nanotechnology1,2 and single-molecule spectroscopy3–5 paves the way for emergent cost-effective organic quantum optical technologies with potential applications in useful devices operating at ambient conditions. We harness a π-conjugated ladder-type polymer strongly coupled to a microcavity forming hybrid light–matter states, so-called exciton-polaritons, to create exciton-polariton condensates with quantum fluid properties. Obeying Bose statistics, exciton-polaritons exhibit an extreme nonlinearity when undergoing bosonic stimulation6, which we have managed to trigger at the single-photon level, thereby providing an efficient way for all-optical ultrafast control over the macroscopic condensate wavefunction. Here, we utilize stable excitons dressed with high-energy molecular vibrations, allowing for single-photon nonlinear operation at ambient conditions.
But Arvind Krishna says that some hard quantum physics problems await as the market pushes for larger and larger quantum systems.
Topological quantum computing is probably one of the most promising fields of the future which would greatly boost machine learning that already employs combined elements of cognitive, evolutionary and neuromorphic engineering. Post-singularity artificial superintelligence could have complete access to their own source code — a level of self-awareness presently beyond human capability. That would allow the post-singularity syntelligence to create myriad virtual worlds right out of its own superimagination. We can’t completely rule out a possibility that we’re part of that simulated reality right now. At the same time, we ourselves are moving towards the point of Theogenesis where we can rightly call ourselves cybergods.
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In a new study from Skoltech and the University of Kentucky, researchers found a new connection between quantum information and quantum field theory. This work attests to the growing role of quantum information theory across various areas of physics. The paper was published in the journal Physical Review Letters.
Quantum information plays an increasingly important role as an organizing principle connecting various branches of physics. In particular, the theory of quantum error correction, which describes how to protect and recover information in quantum computers and other complex interacting systems, has become one of the building blocks of the modern understanding of quantum gravity.
“Normally, information stored in physical systems is localized. Say, a computer file occupies a particular small area of the hard drive. By “error” we mean any unforeseen or undesired interaction which scrambles information over an extended area. In our example, pieces of the computer file would be scattered over different areas of the hard drive. Error correcting codes are mathematical protocols that allow collecting these pieces together to recover the original information. They are in heavy use in data storage and communication systems. Quantum error correcting codes play a similar role in cases when the quantum nature of the physical system is important,” Anatoly Dymarsky, Associate Professor at the Skoltech Center for Energy Science and Technology (CEST), explains.
Electrons in two-dimensional hexagonal materials have an extra degree of freedom, the valley pseudospin, that can be used to encode and process quantum information. Valley-selective excitations, governed by the circularly polarized light resonant with the material’s bandgap, are the foundation of valleytronics. It is often assumed that achieving valley selective excitation in pristine graphene with all-optical means is not possible due to the inversion symmetry of the system. Here, we demonstrate that both valley-selective excitation and valley-selective high-harmonic generation can be achieved in pristine graphene by using a combination of two counter-rotating circularly polarized fields, the fundamental and its second harmonic. Controlling the relative phase between the two colors allows us to select the valleys where the electron–hole pairs and higher-order harmonics are generated. We also describe an all-optical method for measuring valley polarization in graphene with a weak probe pulse. This work offers a robust recipe to write and read valley-selective electron excitations in materials with zero bandgap and zero Berry curvature.
