Science Daily March 30, 2022 In previous experiments, the light intensity for realizing Floquet state (where the original quantum state is replicated when light is irradiated on matters) in solids was enormous due to the high frequency of light. An international team of researchers (South Korea, Japan) succeeded in the experimental realization of the steady Floquet state in a graphene Josephson junction (GJJ) by irradiating continuous microwaves on it. The intensity of the light was decreased to one trillionth the value of previous experiments, significantly reducing the heat generation and enabling continuously long-lasting Floquet states. They also developed a novel […]
Tag Archives: Quantum technology
Breakthrough in quantum sensing provides new material to make qubits
Phys.org March 9, 2022 Being atomically thin and amenable to external controls, 2D materials offer a new paradigm for the realization of patterned qubit fabrication and operation at room temperature for quantum information sciences applications. An international team of researchers (USA – Temple University, Northeastern University, Taiwan) has shown that the antisite defect in 2D transition metal dichalcogenides (TMDs) can provide a controllable solid-state spin qubit system. Using high-throughput atomistic simulations, they identified several neutral antisite defects in TMDs that lie deep in the bulk band gap and host a paramagnetic triplet ground state. The analysis revealed the presence of […]
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 […]
Two-dimensional material could store quantum information at room temperature
Phys.org February 11, 2022 Spins in two-dimensional materials offer an advantage, as the reduced dimensionality enables feasible on-chip integration into devices. An international team of researchers (UK, Australia) has reported room-temperature optically detected magnetic resonance (ODMR) from single carbon-related defects in hexagonal boron nitride with up to 100 times stronger contrast than the ensemble average. They identified two distinct bunching timescales in the second-order intensity-correlation measurements for ODMR-active defects, but only one for those without an ODMR response. They observed either positive or negative ODMR signal for each defect. Based on kinematic models, they related this bipolarity to highly tunable […]
Cooling matter from a distance
Science Daily February 2, 2022 Researchers in Switzerland succeeded in forming a control loop consisting of two quantum systems separated by one meter. Within this loop a vibrating membrane was cooled by a cloud of atoms, and the two systems were coupled to one another by laser light. As one of the systems acts as a control unit for the other, no measurement is needed. Instead, the control system is configured to bring the target system into a desired state by means of coherent quantum mechanical interaction. They successfully used this coherent feedback mechanism to reduce the temperature of the […]
New approach transports trapped ions to create entangling gates
Phys.org January 28, 2022 Trapped ions excited with a laser beam can be used to create entangled qubits in quantum information systems but addressing several stationary pairs of ions in a trap requires multiple optical switches and complex controls. Researchers at Georgia Tech Research Institute moved calcium ions held in a surface electrode trap through a stationary bichromatic optical beam potentially integrating the existing transport control into quantum logic operations. Measurements showed that the entangled quantum state of the two qubits transported through the optical beam had a fidelity comparable to entangled states produced by stationary gates performed in the […]
Twin-field quantum key distribution (QKD) across an 830-km fibre
Phys.org January 24, 2022 As the photons carrying signals cannot be amplified or relayed via classical optical techniques to maintain quantum security, the transmission loss of the channel limits its achievable distance. An international team of researchers (Spain, Japan, Canada, China, Russia) has designed an experimental QKD system that could tolerate a channel loss beyond 140 dB and obtain a secure distance of 833.8 km. Furthermore, the optimized four-phase twin-field protocol and set-up make its secure key rate more than two orders of magnitude greater than previous records over similar distances… read more. TECHNICAL ARTICLE 1 , Open Access 2
Mini electricity generator made from quantum dots
Phys.org January 18, 2022 The major challenges toward the exploitation of graphene nanoribbons (GNRs) in electronic applications include reliable contacting, and the preservation of their physical properties upon device integration. An international team of researchers (Switzerland, UK, Germany) described the quantum dot behavior of atomically precise GNRs integrated in a device geometry. The devices consist of a film of aligned five-atom-wide GNRs (5-AGNRs) transferred onto graphene electrodes with a sub 5 nm nanogap. They demonstrated that the narrow-bandgap 5-AGNRs exhibit metal-like behavior at room temperature and single-electron transistor behavior for temperatures below 150 K. They obtained addition energies in the […]
Building a silicon quantum computer chip atom by atom (w/video)
Nanowerk January 12, 2022 Until now, implanting atoms in silicon has been a haphazard process, where a silicon chip gets showered with phosphorus which implant in a random pattern. An international team of researchers (Australia, Germany) has developed a technique to place them in an orderly array, similar to the transistors in conventional semiconductors computer chips. They embedded phosphorus ions, precisely counting each one, in a silicon substrate creating a qubit using advanced technology developed for sensitive x-ray detectors and a special atomic force microscope. They drilled a tiny hole in the cantilever, so that when it was showered with phosphorus […]
A new look at quantum radar suggests it might boost accuracy more than thought
Phys.org January 10, 2022 Despite the many proposals for quantum radar, none have delineated the ultimate quantum limit on ranging accuracy. A team of researchers in the US (University of Arizona, MIT) has derived that limit through continuous-time quantum analysis. They showed that quantum illumination ranging—a quantum pulse-compression radar that exploits the entanglement between a high time-bandwidth product transmitted signal pulse and a high time-bandwidth product retained idler pulse—achieves that limit. They also showed that quantum illumination ranging offers mean-squared range-delay accuracy that can be tens of dB better than that of a classical pulse-compression radar of the same pulse […]