Phys.org January 17, 2023 Optically active defects in 2D materials, such as hexagonal boron nitride (hBN) and transition-metal dichalcogenides (TMDs), are an attractive class of single-photon emitters. An international team of researchers (USA – UC Santa Barbara, Japan) has demonstrated a novel approach to precisely align and embed hBN and TMDs within background-free silicon nitride microring resonators. Through the Purcell effect, high-purity hBN emitters exhibited a cavity-enhanced spectral coupling efficiency of up to 46% at room temperature, exceeding the theoretical limit (up to 40%) for cavity-free waveguide-emitter coupling and demonstrated nearly a 1 order of magnitude improvement over previous work. […]
Tag Archives: Quantum technology
New spin control method brings billion-qubit quantum chips closer
Phys.org January 12, 2023 The electron spin forms a qubit that is naturally robust to electric fluctuations. However, a common control strategy is the integration of micromagnets to enhance the coupling between spins and electric fields, which, in turn, hampers noise immunity and adds architectural complexity. An international team of researchers (Australia, Japan, Germany, Canada) used switchable interaction between spins and orbital motion of electrons in silicon quantum dots, without a micromagnet. The weak effects of relativistic spin–orbit interaction in silicon were enhanced, leading to a speed up in Rabi frequency by a factor of up to 650 by controlling […]
Chip circuit for light could be applied to quantum computations
Phys.org January 3, 2023 While substantial progress has been made, separately, towards ultra-low loss chip-scale photonic circuits and high brightness single-photon sources, integration of these technologies has remained elusive. An international team of researchers (USA – National Institute of Standards and Technology, University of Maryland, research org., MIT, UC Santa Barbara, industry, Brazil, South Korea) integrated a quantum emitter single-photon source with a wafer-scale, ultra-low loss silicon nitride photonic circuit to demonstrate triggered and pure single-photon emission into a Si3N4 photonic circuit with ≈ 1 dB/m propagation loss at a wavelength of ≈ 930 nm. They observed resonance fluorescence in the strong drive regime, showing promise […]
Researchers develop a light source that produces two entangled light beams
Phys.org January 3, 2023 In quantum entanglement when the systems interact with their surroundings, they almost immediately become disentangled. An international team of researchers (Brazil, USA – University of Oklahoma) produced a light source that produced two entangled light beams. The twin beams generated with a doubly resonant optical parameter oscillator (OPO) based on four-wave mixing in hot 85Rb vapor above threshold. They reconstructed the covariance matrix for several configurations and based on a full picture of the four-side band mode state, they studied entanglement between all possible bipartitions. They showed a robust generation of entanglement with stronger generation for […]
Researchers release roadmap for the development of quantum information technologies
Phys.org December 14, 2022 Q-NEXT, a U.S. Department of Energy (DOE) National Quantum Information Science Research Center, has created a roadmap for quantum interconnects research and its impact for quantum information science and technology. Q-NEXT members and participants are from academia, industry, and DOE national laboratories. The roadmap addresses the role of quantum interconnects in three emerging areas of quantum information: computing, communication, and sensing. The roadmap reviews the materials, components and systems used for these purposes; summarizes relevant scientific questions and issues; and addresses the most pressing research needs. It distills these considerations into recommendations for strategic science and […]
A scalable quantum memory with a lifetime over 2 seconds and integrated error detection
Phys.org November 28, 2022 Because of their long coherence times and efficient optical interface, color centers in diamond are promising candidates for quantum memory nodes. Researchers at Harvard University integrated two-qubit network node based on silicon-vacancy centers (SiVs) in diamond nanophotonic cavities. The qubit register consisted of the SiV electron spin acting as a communication qubit and the strongly coupled silicon-29 nuclear spin acting as a memory qubit with a quantum memory time exceeding 2 seconds. They demonstrated electron-photon entangling gates at temperatures up to 1.5 kelvin and nucleus-photon entangling gates up to 4.3 kelvin and efficient error detection in […]
Quantum technology reaches unprecedented control over captured light
Phys.org September 27, 2022 An international team of researchers (Sweden, Japan) has developed a technique to overcome to noise and interference in quantum systems. Their technique could create any of the previously demonstrated states and the cubic phase state. They used a sequence of interleaved selective number-dependent arbitrary phase (SNAP) gates and displacements. The state preparation was optimized in two steps – first they used a gradient-descent algorithm to optimize the parameters of the SNAP and displacement gates; then optimized the envelope of the pulses implementing the SNAP gates. The results showed that this way of creating highly nonclassical states […]
Coupling of electron-hole pairs
Nanowerk September 5, 2022 In two-layered molybdenum disulfide, excitation with light produces two different types of electron-hole pairs: intralayer pairs, in which the electron and hole are localized in the same layer of the material, and interlayer pairs, whose hole and electron are in different layers and are therefore spatially separate from one another. The intralayer pairs interact strongly with light. The interlayer excitons are much dimmer but can be shifted to different energies and therefore allow researchers to adjust the absorbed wavelength. They exhibit very strong, nonlinear interactions with one another which play an essential role in many of […]
Why ‘erasure’ could be key to practical quantum computing
Phys.org September 1, 2022 The fundamental challenge to quantum computers is that the operations are noisy. Rather than focusing solely on reducing the number of errors a team of researchers in the US (Yale University, University of Wisconsin-Madison, Princeton) made errors more visible. They delved deeply into the actual physical causes of error and engineered their system so that the most common source of error effectively eliminates, rather than simply corrupting, the damaged data leading to “erasure error,” which is fundamentally easier to weed out than data that is corrupted but still looks like all the other data. Erasure errors […]
A quantum pump without a crank
Phys.org August 22, 2022 The pumping process can have topological origins, when considering the motion of quantum particles in spatially and temporally periodic potentials. However, the periodic evolution that drives these pumps has always been assumed to be imparted from outside. Researchers in Switzerland found an emergent mechanism for pumping in a quantum gas coupled to an optical resonator, where they observed a particle current without applying a periodic drive. The pumping potential experienced by the atoms is formed by the self-consistent cavity field interfering with the static laser field driving the atoms. The cavity field evolves between its two […]