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 […]
Tag Archives: Qubits
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 […]
How a novel radio frequency control system enhances quantum computers
Phys.org November 9, 2021 Researchers at the Lawrence Berkeley National Laboratory have demonstrated a new way to control qubits by substituting the larger, more costly traditional RF control systems with smaller interactive mixing modules. The modular system has high -reliability, delivering high-resolution, low-noise RF signals needed to manipulate and measure the superconducting qubit at room temperature. To do so, they shifted the qubit manipulation and measurement signal frequency between the electronics baseband and the quantum system. According to the researchers their system could be expanded to other quantum information science platforms, and RF mixing can be expanded to higher frequencies. […]
Making progress towards quantum technologies based on magnetic molecules
Nanowerk October 15, 2021 Electrical control of spins at the nanoscale offers significant architectural advantages in spintronics. However, the electric-field sensitivities reported so far are rather weak. An international team of researchers (UK, Spain) showed that one path is to identify an energy scale in the spin spectrum that is associated with a structural degree of freedom with a substantial electrical polarizability. They studied an example of a molecular nanomagnet in which a small structural distortion establishes clock transitions in the spin spectrum; the fact that this distortion is associated with an electric dipole allowed them to control the clock-transition energy […]
All-nitride superconducting qubit made on a silicon substrate
Science Daily September 20, 2021 Researchers in Japan have developed superconducting qubits based on NbN/AlN/NbN epitaxial Josephson junctions on silicon substrates which promise to overcome the drawbacks of qubits based on Al/AlOx/Al junctions. The all-nitride qubits have great advantages such as chemical stability against oxidation, resulting in fewer two-level fluctuators, feasibility for epitaxial tunnel barriers that reduce energy relaxation and dephasing, and a larger superconducting gap of ~5.2 meV for NbN, compared to ~0.3 meV for aluminum, which suppresses the excitation of quasiparticles. By replacing conventional MgO by a silicon substrate with a TiN buffer layer for epitaxial growth of […]
Quantum systems learn joint computing
EurekAlert February 24,2021 An international team of researchers (Germany, Spain) succeeded in connecting two qubit modules across a 60-meter distance in such a way that they effectively form a basic quantum computer with two qubits. They performed a quantum computing operation between two independent qubit setups in different laboratories. To generate entanglement between qubits for quantum computations they employed modules consisting of a single atom as a qubit that is positioned amidst two mirrors. Between these modules, they sent a photon, that is transported in the optical fiber. This photon is then entangled with the quantum states of the qubits […]
Blueprint for fault-tolerant qubits
EurekAlert February 18, 2021 The application of active error correction in a quantum computer is very complex and comes with an extensive use of hardware. An international team of researchers (Germany, Switzerland, the Netherlands) has proposed a design for a circuit with passive error correction. The circuit is designed in such a way that it is already inherently protected against environmental noise while still controllable. The concept thus bypasses the need for active stabilization in a highly hardware-efficient manner and would therefore be a promising candidate for a future large-scale quantum processor that has many qubits. By implementing a gyrator […]