Science Daily June 1, 2023 Quantum light sources in which coupling between single photons and phonons can be controlled and harnessed enables quantum information transduction. Researchers at the University of Washington created quantum emitters featuring highly tunable coupling between excitons and phonons. The quantum emitters were formed in strain-induced quantum dots created in homobilayer WSe2. The colocalization of quantum-confined interlayer excitons and terahertz interlayer breathing-mode phonons, which directly modulated the exciton energy, led to a uniquely strong phonon coupling to single-photon emission. Due to the vertical dipole moment of the interlayer exciton, the phonon–photon interaction was electrically tunable to be […]
Tag Archives: Qubits
Proposed perovskite-based device combines aspects of electronics and photonics
Phys.org May 12, 2023 Hybrid perovskites have emerged as a promising material candidate for exciton-polariton (polariton) optoelectronics. Many applications demand precise control of polariton interactions. Thus far, the primary mechanisms by which polaritons relax in perovskites remain unclear. An international team of researchers (USA – MIT, Spain, Italy) sandwiched perovskite in between two precisely spaced reflective surfaces and stimulated them with laser beams. Then they were able to directly control the momentum of exciton-polariton pairs. The combined sate could be perturbed either with light or charge in a more energy-efficient manner. Halide perovskites harvest light well, and turn photons into […]
On-demand storage of photonic qubits at telecom wavelengths
Phys.org December 6, 2022 Researchers in China processed a fiber-integrated quantum memory at telecom wavelengths based on a laser-written waveguide fabricated in an erbium-doped yttrium silicate. Both ends of the waveguide memory were directly connected with fiber arrays with a fiber-to-fiber efficiency of 51%. Storage fidelity of 98.3(1)% was obtained for time-bin qubits encoded with single-photon-level coherent pulses, which is far beyond the maximal fidelity that can be achieved with a classical measure and prepared strategy. This device featured high reliability and easy scalability, and it can be directly integrated into fiber networks, which could play an essential role in […]
Unimon – A new qubit to boost quantum computers for useful applications
Nanowerk November 15, 2022 Superconducting qubits seem promising for useful quantum computers, but the currently wide-spread qubit designs and techniques do not yet provide high enough performance. Researchers in Finland have developed a superconducting-qubit type, the unimon, which combines the desired properties of increased anharmonicity, full insensitivity to dc charge noise, reduced sensitivity to flux noise, and a simple structure consisting only of a single Josephson junction in a resonator. In agreement with their quantum models, they measured the qubit frequency and increased anharmonicity at the optimal operation point. It yielded, 99.9% and 99.8% fidelity for 13 ns single-qubit gates on […]
What quantum information and snowflakes have in common, and what we can do about it
Science Daily June 15, 2022 Transducing quantum signals between disparate regimes of the electro-magnetic spectrum remains an outstanding goal. Many remote entanglement protocols require multiple qubit gates both preceding and following the upconversion of the quantum state, and thus an ideal transducer should impart minimal backaction on the qubit. A team of researchers in the US (University of Colorado, NIST) demonstrated readout of a superconducting transmon qubit through a low-backaction electro-optomechanical transducer. The modular nature of the transducer and circuit quantum electrodynamics system used in this work enabled complete isolation of the qubit from optical photons, and the backaction on […]
Hybrid quantum bit based on topological insulators
Science Daily April 14, 2022 Topological qubits are considered to be particularly robust and largely immune to external sources of decoherence and appear to enable fast switching times comparable to those achieved by the conventional superconducting qubits used in current quantum processors. However, it is not yet clear whether we will ever succeed in producing topological qubits as a suitable material basis is still lacking to experimentally generate the special quasiparticles required for this without any doubt. An international team of researchers (Germany, UK, Denmark, the Netherlands) implemented superconducting transmon qubits with (Bi0.06Sb0.94)2Te3 topological insulator. According to the team microwave […]
Researchers Set Record by Preserving Quantum States in Silicon Carbide for More Than Five Seconds
SciTech Daily March 13, 2022 Inability to easily read the information held in qubits, and the short coherence of qubits are impediments to the many technological applications of quantum science such as hacker proof communications networks and quantum computers. An international team of researchers (USA – University of Chicago, Argonne National Laboratory, Japan, Sweden) has demonstrated single-shot readout of single defects in SiC via spin-to-charge conversion, whereby the defect’s spin state was mapped onto a long-lived charge state. With this technique, they achieved over 80% readout fidelity without pre- or post-selection, resulting in a high signal-to-noise ratio that enabled them […]
Using two different elements creates new possibilities in hybrid atomic quantum computers
Nanowerk March 2, 2022 Researchers at the University of Chicago have introduced a dual-element atom array with individual control of single rubidium and cesium atoms. They were placed in arrays with up to 512 trapping sites and observed negligible crosstalk between the two elements. Furthermore, by continuously reloading one atomic element while maintaining an array of the other, they demonstrated a new continuous operation mode for atom arrays without any off-time. According to the researchers the results enable avenues for auxiliary-qubit-assisted quantum protocols such as quantum nondemolition measurements and quantum error correction, as well as continuously operating quantum processors and […]
Tiny materials lead to a big advance in quantum computing
MIT News January 27, 2022 An international team of researchers (USA – MIT, MIT Lincoln Laboratory, Japan) used hexagonal boron nitride to build a parallel-plate capacitor for a qubit. To fabricate the capacitor, they sandwiched hexagonal boron nitride between very thin layers of another van der Waals material, niobium diselenide and connected the capacitor to the existing structure and cooled the qubit to 20 millikelvins (-273.13 C). The resulting qubit was about 100 times smaller than what they made with traditional techniques on the same chip. The coherence time, or lifetime, of the qubit was only a few microseconds shorter […]
Scientists document the presence of quantum spin liquids, a never-before-seen state of matter
Phys.org December 2, 2021 To reproduce the microscopic physics found in condensed matter systems an international team of researchers (USA – Harvard University, MIT, Austria) used a simulator that allows the researchers to create programmable shapes like squares, honeycombs, or triangular lattices to engineer different interactions and entanglements between ultracold atoms. Quantum spin liquids display none of that magnetic order because, essentially, there is a third spin added, turning the checker box pattern to a triangular pattern making it a “frustrated” magnet where the electron spins can’t stabilize in a single direction. The researchers used the simulator to create their […]