Fifty perfect photons for ‘quantum supremacy’

Phys.org  June 23, 2020 About 50 quantum building blocks are needed to solve problems whether they are in the form of photons or qubits. Photons can operate at room temperatures and they are more stable. But they must be perfect to get to the critical number of 50. An international team of researchers (the Netherlands, Germany) found that by playing with the crystal structure of the light source and dividing them into domains, it was possible to produce light with the desired properties. Varying the domains, however, is required for better tailoring of the light properties…read more. TECHNICAL ARTICLE

Light from stretchable sheets of atoms for quantum technologies

EurekAlert  April 16, 2020 Unlike other nanomaterials used as quantum light sources, such as diamond, silicon carbide or gallium nitride hexagonal boron nitride is not brittle and comes with the unique stretchable mechanical properties of a van der Waals crystal. However, their spectral inhomogeneity currently limits their potential applications. Researchers in Australia applied tensile strain to quantum emitters embedded in few‐layer hBN films. They observed both red and blue spectral shifts with tuning magnitudes up to 65 meV. Rotation of the optical dipole in response to strain suggested the presence of a second excited state. They developed a theoretical model […]

Scientists Find Yet Another Way to Get Qubits Working at Room Temperature

Science Alert  March 22, 2020 Defect-based quantum systems are often complicated by charge-state instabilities and interference by phonons, which can diminish spin-initialization fidelities and limit room-temperature operation. An international team of researchers (Hungary, Sweden, USA – Argonne National Laboratory, University of Chicago, IBM, Russia) has identified a pathway around these drawbacks by showing that an engineered quantum well can stabilize the charge state of a qubit. Using density-functional theory and experimental synchrotron X-ray diffraction studies they constructed a model for previously unattributed point defect centers in silicon carbide as a near-stacking fault axial divacancy and showed how this model explains […]

In leap for quantum computing, silicon quantum bits establish a long-distance relationship

EurekAlert  December 25, 2019 Silicon spin qubits have several advantages over superconducting qubits – they retain their quantum state longer than competing qubit technologies and they could be manufactured at low cost. A team of researchers in the US (Princeton University, industry) connected the qubits via a “wire” which is a narrow cavity containing a photon that picks up the message from one qubit and transmits it to the next qubit. The two qubits were located about half a centimeter apart. The team succeeded in tuning both qubits independently of each other while still coupling them to the photon. An […]

Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits

Phys.org  July 13, 2018 In their experiments, an international team of researchers (Australia, USA – Purdue University) has confirmed the ability to tune neighbouring qubits into resonance without impacting each other. Creating engineered phosphorus molecules with different separations between the atoms within the molecule allows for families of qubits with different control frequencies. Each molecule can be operated individually by selecting the frequency that controls its electron spin. It creates a built-in address which will provide significant benefits for building a silicon quantum computer. By engineering the atomic placement of the atoms within the qubits in the silicon chip, the […]