Science Alert June 22, 2022 Researchers in Australia have created a functional quantum processor and tested it by modeling a small molecule in which each atom has multiple quantum states. They used a scanning tunneling microscope in an ultra-high vacuum to place quantum dots with sub-nanometer precision. The trickiest parts were figuring out: exactly how many atoms of phosphorus should be in each quantum dot; exactly how far apart each dot should be; and then engineering a machine that could place the tiny dots in exactly the right arrangement inside the silicon chip. The final quantum chip contained 10 quantum […]
Tag Archives: Quantum technology
Improving quantum sensors by measuring the orientation of coherent spins inside a diamond lattice
Phys.org June 16, 2022 Researchers in Japan have developed a new method for implementing magnetic field measurements in nitrogen-vacancy centers. The spin state of an extra electron at this site can be read or coherently manipulated using pulses of light. They used an “inverse Cotton-Mouton” effect to test their method. They used light of different polarizations to create tiny controlled local magnetic fields. They have demonstrated that by measuring the orientation of coherent spins inside a diamond lattice, the magnetic fields can be measured even over very short times. The team hopes that this work will help enable quantum spintronic […]
Emulating impossible ‘unipolar’ laser pulses paves the way for processing quantum information
Science Daily May 24, 2022 Key applications such as THz scanning tunnelling microscopy or electronic devices operating at optical clock rates call for ultimately short, almost unipolar waveforms, at megahertz (MHz) repetition rates. An international team of researchers (Germany, USA – University of Michigan) has developed a flexible and scalable scheme for the generation of strong phase-locked THz pulses based on shift currents in type-II-aligned epitaxial semiconductor heterostructures. The measured THz waveforms exhibit only 0.45 optical cycles at their centre frequency within the full width at half maximum of the intensity envelope, peak fields above 1.1 kV cm−1 and spectral components up […]
Thin quantum wires work better with less insulating coatings
Phys.org May 4, 2022 Thin semiconducting wires, referred to as quantum wires, are often coated in insulating materials. Previous studies have explored how the mismatch between the insulating properties of both materials can influence their performance. Researchers in Vietnam have shown that thinner wires with less insulating coatings can improve the mobility of the electrons they carry. Previous models have presented conflicting conclusions about the ability of electrons to move through the wire, depending on whether coatings are more or less insulating than the semiconductor. The researchers considered the case where electrons are allowed to cross the outer boundary of […]
Two teams use neutral atoms to create quantum circuits
Phys.org April 22, 2022 Gate-model quantum computers promise to solve currently intractable computational problems if they can be operated at scale with long coherence times and high-fidelity logic. Neutral-atom hyperfine qubits provide inherent scalability owing to their identical characteristics, long coherence times and ability to be trapped in dense, multidimensional arrays. Combined with the strong entangling interactions provided by Rydberg states all the necessary characteristics for quantum computation are available. An international team of researchers (USA – University of Central Florida, Harvard University, University of Wisconsin-Madison, industry, MIT, UK, Austria,) demonstrated several quantum algorithms on a programmable gate-model neutral-atom quantum […]
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 […]
Tailored single photons: Optical control of photons as the key to new technologies
Nanowerk April 6, 2022 Several different approaches to realize solid-state quantum emitters with high performance have been pursued and different concepts for energy tuning have been established. However, the properties of the emitted photons are always defined by the individual quantum emitter and can therefore not be controlled with full flexibility. An international team of researchers (Germany, USA – University of Arizona) has developed an all-optical nonlinear method to tailor and control the single photon emission. They demonstrated a laser-controlled down-conversion process from an excited state of a semiconductor quantum three-level system. Based on this concept, they realized energy tuning […]
Engineering the quantum states in solids using light
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 […]
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 […]