Science Daily May 22, 2018 The uncontrolled interaction of a quantum system with its environment is detrimental for quantum coherence. An international team of researchers (USA – Harvard University, Sandia National Laboratory, UK) used a nano-electro-mechanical system to mitigate the effect of thermal phonons on a spin qubit, the silicon vacancy color center, without changing the system temperature. By controlling the strain environment of the colour centre, they tuned its electronic levels to probe, control, and eventually suppress the interaction of its spin with the thermal bath. Strain control provided both large tunability of the optical transitions and significantly improved […]
Category Archives: Quantum science
Entangled atoms shine in unison
Phys.org May 18, 2018 A team of international researchers (Austria, Australia, Czech Republic) compared the photon interference produced by entangled and non-entangled barium atoms. The measured difference of the interference fringes directly corresponds to the amount of entanglement in the atoms which helps to characterize the entanglement fully optically. They demonstrated that the interference signal is highly sensitive to environmental factors at the location of the atoms. The demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the Earth’s magnetic field… read more. TECHNICAL ARTICLE
Can a quantum drum vibrate and stand still at the same time?
Science Daily May 18, 2018 The preparation of mechanical quantum superposition states remains outstanding due to weak coupling and thermal decoherence. An international team of researchers (Australia, UK) present a novel optomechanical scheme that significantly relaxes these requirements allowing the preparation of quantum superposition states of motion of a mechanical resonator by exploiting the nonlinearity of multi-photon quantum measurements. The method can generate non-classical mechanical states without the need for strong single-photon coupling, is resilient against optical loss, and offers more favourable scaling against initial mechanical thermal occupation than existing schemes. It offers potential for the development of powerful new […]
The Big Bell Test: Global physics experiment challenges Einstein
Science Daily May 9, 2018 A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Twelve laboratories on five continents, 13 experiments tested local realism using photons, single atoms, atomic ensembles and superconducting devices. More than 100,000 people around the world playing an online video game generated 97,347,490 binary choices. The observed correlations strongly contradict local realism and other realistic positions in bipartite and tripartite scenarios…read more. TECHNICAL ARTICLE
The apparent inner calm of quantum materials
Nanowerk May 7, 2018 It was predicted that a set of topological excitations in a quantum material is likely to induce a phase transition. An international team of researchers (France, Switzerland, Sweden, Germany, Japan) has provided experimental confirmation of this theory in BACOVO (BaCo2V2O8). They found a novel topological phase transition in BACOVO, governed not by a single type of topological excitation, but by two different ones. In addition, they were able to choose which of the two sets would dominate the other. These results open a whole range of possibilities in quantum physics research… read more. Open Access TECHNICAL […]
Playing quantum catch in new research
Science Daily April 23, 2018 For a quantum computer to run more complex algorithms, qubits must be interfaced with each other. Researchers at Yale University ‘pitched’ a qubit from one physical point in a microwave cavity to a separate point in a different cavity while it preserved and caught the information. They carefully shape their pitch-and-catch over time, so that both ends of the transaction are in sync. Pitch and catch also includes quantum entanglement. In this instance, it means the pitcher is pitching and not pitching, simultaneously. Remote entanglement will be crucial in quantum networks… read more. Open Access […]
Physicists Just Broke a Quantum Record, Taking Entanglement to a Spooky New Level
Science Alert April 16, 2018 An international team of researchers (Austria, Germany) used an ion trap to confine calcium ions using a magnetic field. They used lasers to entangle the ions, creating a 20-qubit system, with each qubit encoded into the electronic state of a trapped atomic ion. Their quantum states can be individually controlled, and they were able to individually read and address each of the qubits. The team were able to get the calcium ions to entangle with two, three, or occasionally even four other calcium ions in the system… read more. Open Access TECHNICAL ARTICLE
Quantum shift shows itself in coupled light and matter
Science Daily April 16, 2018 An international team of researchers (USA – Rice University, Argonne National Laboratory, Purdue University, Japan) created resonance frequency shift in solid gallium arsenide in a strong perpendicular magnetic field. They hybridize with the “vacuum” electromagnetic field in the cavity to form polaritons. They have demonstrated Bloch–Siegert shift, which is induced by the ultra-strong coupling of matter with the counter-rotating component of the vacuum fluctuation field in a cavity. The research could aid in the development of quantum computers… read more. Open Access TECHNICAL ARTICLE
Easing uncertainty: How Heisenberg’s uncertainty principle can be relaxed
Science Daily April 2, 2018 Researchers in Switzerland used sequences of multiple periodic position and momentum measurements to demonstrate that varying the period controls whether one measurement disturbs the state of the following one. At specific values of the period, they found that such measurements can avoid disturbance, whereas other choices produce strong disturbance. Modular position and momentum measurement are central components of several proposals for quantum computing and precision-measurement protocols that exploit periodic functions of position and momentum to escape Heisenberg’s uncertainty principle. The research provides a fundamental ingredient — measurement — for such applications, thus bringing them closer […]
A new kind of quantum bits in two dimensions
Nanowerk March 19, 2018 An international team of researchers (Germany, Austria, Hungary, UK) succeeded in developing a new type of quantum dots by combining graphene and hexagonal boron nitride, also a single layer of material quite like graphene except that it is insulating. The two layers cannot perfectly match when put one on top of the other resulting in an extremely regular wave-like spatial oscillation of the graphene layer out of the perfect plane. The potential landscape created by the regular superstructure allows for accurately placing the quantum dot, or even moving it continuously and thus smoothly changing its properties… […]