Phys.org April 15, 2024 Nonlocality is crucial for device-independent technologies like quantum key distribution and randomness generation. It quickly deteriorates in the presence of noise, and restoring nonlocal correlations requires additional resources incurring a significant resource overhead. An international team of researchers (Australia, France, USA – NIST, Boulder, CO) experimentally demonstrated that single copies of Bell-local states, incapable of violating any standard Bell inequality, could give rise to nonlocality after being embedded into a quantum network of multiple parties. They subjected the initial entangled state to a quantum channel that broadcast part of the state to two independent receivers and […]
Tag Archives: Quantum technology
Research team takes a fundamental step toward a functioning quantum internet
Phys.org February 7, 2024 Quantum repeater networks require independent absorptive quantum memories capable of storing and retrieving indistinguishable photons to perform high-repetition entanglement swapping operations. An international team of researchers (USA – Stony Brook University, industry, Brookhaven National Laboratory, Italy) performed Hong-Ou-Mandel (HOM) interference between photonic polarization states and single-photon-level pulses stored and retrieved from two sets of independent room-temperature quantum memories. They showed that the storage and retrieval of polarization states from quantum memories did not degrade the HOM visibility for few-photon-level polarization states in a dual-rail configuration. For single-photon-level pulses, they measured the HOM visibility with various levels […]
Combining diamond and lithium niobate as a core component for future quantum technologies
Nanowerk December 15, 2023 Negatively charged group-IV color centers in diamond are promising candidates for quantum memories as they combine long storage times with excellent optical emission properties and an optically addressable spin state. However, as a material, diamond lacks the many functionalities needed to realize scalable quantum systems. Thin-film lithium niobate (TFLN), in contrast, offers several useful photonic nonlinearities, including the electro-optic effect, piezoelectricity, and capabilities for periodically poled quasi-phase matching. Researchers at Stanford University have presented highly efficient heterogeneous integration of diamond nanobeams containing negatively charged silicon-vacancy (SiV) centers with TFLN waveguides. They observed greater than 90% transmission […]
A linear path to efficient quantum technologies
Nanowerk September 12, 2023 Bell-state projections serve as a fundamental basis for most quantum communication and computing protocols today. However, with current Bell-state measurement schemes based on linear optics, only two of four Bell states can be identified, which means that the maximum success probability of this vital step cannot exceed 50%. Researchers in Germany experimentally demonstrated a scheme that amended the original measurement with additional modes in the form of ancillary photons, which led to a more complex measurement pattern, and ultimately a higher success probability of 62.5%. Experimentally, they achieved a success probability of (57.9 ± 1.4)%, a […]
Scientists develop fermionic quantum processor
Phys.org August 23, 2023 Although qubit-based quantum computers can potentially simulate the properties of many-body fermionic systems more efficiently than classical devices, encoding nonlocal fermionic statistics introduces an overhead in the required resources, limiting their applicability on near-term architectures. An international team of researchers (Austria, USA – Harvard University, University of Colorado) has demonstrated a fermionic quantum processor, where fermionic models were locally encoded in a fermionic register and simulated in a hardware-efficient manner using fermionic gates. They considered fermionic atoms in programmable tweezer arrays and developed different protocols to implement nonlocal gates, guaranteeing Fermi statistics at the hardware level. […]
Fluxonium Qubit Retains Information For 1.43 Milliseconds – 10x Longer Than Before
Science Alert July 6, 2023 An international team of researchers (USA- University of Maryland, Switzerland) has built a fluxonium qubit that could retain information for 1.43 milliseconds. The superconducting fluxonium qubit had uncorrected coherence time T∗2=1.48±0.13ms, exceeding the state of the art for transmons by an order of magnitude. The average gate fidelity was benchmarked at 0.99991(1). Even in the millisecond range, the coherence time was limited by material absorption and could be further improved with a more rigorous fabrication. According to the researchers their demonstration may be useful for suppressing errors in the next generation quantum processors… read more. […]
New research on self-locking light sources presents opportunities for quantum technologies
Nanowerk June 19, 2023 An international team of researchers (Argentina, Germany) demonstrated that light emitters with different resonance frequencies can asynchronously self-lock their relative energies by exchanging mechanical energy. They introduced polaromechanical metamaterials, two-dimensional arrays of μm-sized traps confining zero-dimensional light-matter polariton fluids and GHz phonons. A strong exciton-mediated polariton-phonon interaction induced a time-dependent inter-site polariton coupling J(t) with remarkable consequences for the dynamics. When locally perturbed by continuous wave optical excitation, a mechanical self-oscillation started and polaritons responded by locking the energy detuning between neighbor sites at integer multiples of the phonon energy showing asynchronous locking involving the polariton […]
New technique in error-prone quantum computing makes classical computers sweat
Phys.org June 14, 2023 The widely accepted solution to noise in quantum computing is the implementation of fault-tolerant quantum circuits, which is out of reach for current processors. A team of researchers in the US (IBM -Yorktown Heights, NY, UC Berkeley) conducted experiments on a noisy 127-qubit processor and demonstrated the measurement of accurate expectation values for circuit volumes at a scale beyond brute-force classical computation. According to the researchers this represents evidence for the utility of quantum computing in a pre-fault-tolerant era. They established the accuracy of the measured expectation values by comparing them with the output of exactly […]
Researchers demonstrate secure information transfer using spatial correlations in quantum entangled beams of light
Phys.org June 5, 2023 The ability to use the temporal and spatial degrees of freedom of quantum states of light to encode and transmit information is crucial for a robust and efficient quantum network. However, the potential offered by the large dimensionality of the spatial degree of freedom remains unfulfilled, as the necessary level of control required to encode information remains elusive. Researchers at the University of Oklahoma encoded information in the distribution of the spatial correlations of entangled twin beams by taking advantage of their dependence on the angular spectrum of the pump needed for four-wave mixing. They showed […]
Qubits put new spin on magnetism: Boosting applications of quantum computers
Science Daily March 17, 2023 Unveiling the fundamental dynamics of naturally or artificially formed magnetic quasicrystals in the presence of an external magnetic field remains a difficult problem that may have implications for the design of information processing devices. Researchers at Los Alamos National Laboratory embedded a qubit magnetic Penrose quasicrystal into a quantum annealer to reproduce the formation of magnetic phases driven by specific physical parameter selections. It allowed them to distinguish a wide range of frustrated magnetic configurations at the single-spin scale. They observed some spins dynamically activate, while others remained static, all within an average magnetization space […]