Phys.org December 19, 2024 For quantum computers the property called “magic” is critical. An international team of researchers (UK, Australia) considered the property of magic, which distinguished the quantum states leading to a genuine computational advantage over classical states when used in algorithms. They examined top-antitop pair production at the LHC produced magic tops, where the amount of magic varied with the kinematics of the final state. They compared results for individual partonic channels and at proton level. They showed that averaging over final states typically increased magic which contrasted with entanglement measures, such as the concurrence, which typically decreased. […]
Tag Archives: Quantum entanglement
Physicists propose Bell test for probing quantum entanglement
Phys.org November 4, 2024 Attosecond physics enables the study of ultrafast coherent electron dynamics in matter upon photoexcitation and photoionization where there has been a strong focus on probing the physical manifestations of internal quantum coherence within the individual parent ion and photoelectron systems. An international team of researchers (UK, Germany) designed theoretically and modelled numerically a direct probe of quantum entanglement in attosecond photoionization in the form of a Bell test and paved the way for the direct observation of entanglement in the context of ultrafast photoionization of many-electron systems. According to the researchers their work provides a novel […]
Physicists ease path to entanglement for quantum sensing
Phys.org August 26, 2024 Spin squeezing is a form of entanglement that reshapes the quantum projection noise to improve measurement precision. An international team of researchers (USA – Harvard University, UC Berkeley, Germany) provided numerical and analytic evidence for the following conjecture: any Hamiltonian exhibiting finite-temperature easy-plane ferromagnetism could be used to generate scalable spin squeezing, thereby enabling quantum-enhanced sensing. It is based on a connection between the quantum Fisher information of pure states and the spontaneous breaking of a continuous symmetry. They demonstrated that spin squeezing exhibits a phase diagram with a sharp transition between scalable squeezing and non-squeezing […]
Significant new discovery in teleportation research — Noise can improve the quality of quantum teleportation
Science Daily May 2, 2024 While quantum teleportation is fueled by a pair of maximally entangled resource qubits, it is vulnerable to decoherence. An international team of researchers (China, Finland) proposed an efficient quantum teleportation protocol in the presence of pure decoherence and without entangled resource qubits entering the Bell-state measurement. They used multipartite hybrid entanglement between the auxiliary qubits and their local environments within the open–quantum system context. With a hybrid-entangled initial state, it is the decoherence that allowed them to achieve high fidelities. They demonstrated their protocol in an all-optical experiment… read more. Open Access TECHNICAL ARTICLE
Deciphering quantum enigmas: The role of nonlocal boxes in defining the boundaries of physical feasibility
Phys.org February 14, 2024 Nonsignaling boxes (NS) are theoretical resources defined by the principle of no-faster-than-light communication. They generalize quantum correlations and some of them are known to collapse communication complexity (CC). However, this collapse is strongly believed to be unachievable in nature. An international team of researchers (France, Canada) provided intuition on which theories are unrealistic. They found a better sufficient condition for a nonlocal box to collapse CC, thus extended the known collapsing region. In some slices of NS, they showed that this condition coincides with an area outside of an ellipse… read more. TECHNICAL ARTICLE Full […]
Research group detects a quantum entanglement wave for the first time using real-space measurements
Science Daily August 23, 2023 Quantum magnets provide a powerful platform to explore complex quantum many-body phenomena. One example is triplon excitations, exotic many-body modes emerging from propagating singlet-triplet transitions. Researchers in Finland engineered a minimal quantum magnet from organic molecules and demonstrated the emergence of dispersive triplon modes in one- and two-dimensional assemblies probed with scanning tunneling microscopy and spectroscopy. According to the researchers their results provide the first demonstration of dispersive triplon excitations from a real-space measurement… read more. TECHNICAL ARTICLE
Wiring up quantum circuits with light
Science Daily May 18, 2023 Quantum entanglement is a key resource in currently developed quantum technologies. Sharing this fragile property between superconducting microwave circuits and optical or atomic systems would enable new functionalities, but this has been hindered by an energy scale mismatch of >104 and the resulting mutually imposed loss and noise. Researchers in Austria created and verified entanglement between microwave and optical fields in a millikelvin environment. Using an optically pulsed superconducting electro-optical device, they showed entanglement between propagating microwave and optical fields in the continuous variable domain. According to the researchers their work not only paves the […]
Generation of color-tunable high-performance LG laser beams via Janus OPO
Phys.org April 24, 2023 Laguerre-Gaussian (LG) modes of light wave can carry the external torque of photons as they move through space. However, LG mode laser sources do not yet exist. An international team of researchers (China, USA – University of Arkansas) has experimentally demonstrated highly efficient, highly pure, broadly tunable, and topological-charge-controllable LG modes from a Janus optical parametric oscillator (OPO). They designed the Janus OPO featuring a two-faced cavity mode to guarantee an efficient evolution from a Gaussian-shaped fundamental pump mode to a desired LG parametric mode. The output LG mode had a tunable wavelength between 1.5 and […]
Generating photons for communication in a quantum computing system
Phys.org October 10, 2020 Realizing a fully connected network of quantum processors requires the ability to distribute quantum entanglement. For distant processing nodes, this can be achieved by generating, routing, and capturing spatially entangled itinerant photons. Researchers at MIT and MIT Lincoln Laboratory have demonstrated the deterministic generation of such photons using superconducting transmon qubits that are directly coupled to a waveguide. They generated two-photon N00N states and showed that the state and spatial entanglement of the emitted photons are tunable via the qubit frequencies. Using quadrature amplitude detection, they reconstructed the moments and correlations of the photonic modes and […]
Scientists Have Demonstrated Quantum Entanglement on a Tiny Satellite Orbiting Earth
Science Alert June 28, 2020 A CubeSat launched last year from the International Space Station was specially designed to shield the entangled photon source from the pressures and temperatures of a launch from Earth. An international team of researchers (Singapore, Turkey, Switzerland, Australia, UK) describes the experiment which is composed of a source of entangled photon pairs coupled to a detector module all controlled by an integrated electronics subsystem. A micro-controller on the experiment interfaces to the satellite’s on-board computer to receive commands and to return science data to ground control. It operates using as little power as possible. The […]