Phys.org February 19, 2020 Researchers in Japan placed a millimeter-sized sphere of yttrium iron garnet in the same resonant cavity as a superconducting Josephson junction qubit, which acted as the sensor. Because of the coupling of the sphere to resonant cavity, and, in turn, between the cavity to the qubit, the qubit could only be excited by an electromagnetic pulse if no magnetic excitations were present in the sphere. Reading the state of the qubit then reveals the state of the sphere. By using single-shot detection instead of averaging, they were able to make the device both highly sensitive and […]
Tag Archives: Quantum technology
Extending Quantum Entanglement Across Town
IEEE Spectrum February 4, 2020 In an experiment researchers in Germany transferred the information contained in a single quantum bit from an atomic state to a single photon, then sent it through some 20 kilometers of fiber optic cable. They generated and observed the entanglement between a rubidium atom and a photon whose wavelength was transformed from 780 nm to the telecom S band at 1522 nm. The researchers found they can preserve on average some 78 percent of the entanglement between the rubidium atom and the fiber optic photon. Their next steps are to build out the full atom-to-photon-to-atom […]
New quantum switch turns metals into insulators
EurekAlert February 3, 2020 In a Mott insulator free flow of electrons is facilitated by reducing the strength of the repulsive interaction between electrons, or by changing the number of electrons. An international team of researchers (Canada, Germany, Switzerland, USA – Lawrence Berkeley National Laboratory, Ohio State University, Oak Ridge National Laboratory, South Korea) explored a way to alter the very quantum nature of the material to enable a metal-insulator transition to occur. They found that in Sr2IrO4 coupling the spin to the orbital angular momentum slows the electrons down to such an extent that they become sensitive to one […]
On the way to quantum networks
Phys.org January 24, 2020 Entanglement between stationary quantum memories and photonic channels is the essential resource for future quantum networks. Together with entanglement distillation, it will enable efficient distribution of quantum states. Researchers in Germany entangled a rubidium atom with a photon and were able to detect the entangled state—which now shares the quantum properties of both particles—after its passage through a 20-km coil of optic fiber. Rubidium atoms emit photons with a wavelength of 780 nanometers which is rapidly absorbed. They built a quantum frequency converter that was specifically designed to increase the wavelength of the emitted photons from […]
What a pair! Coupled quantum dots may offer a new way to store quantum information
Science Daily January 29, 2020 An international team of researchers (USA – NIST, University of Maryland, Japan, Canada) created weakly coupled quantum dots by using the ultrasharp tip of a scanning tunneling microscope as a stylus hovering the tip above an ultracold sheet of graphene briefly increasing the voltage of the tip penetrating through the graphene into an underlying layer of boron nitride. It stripped electrons from atomic impurities in the layer and created electric charge which corralled freely floating electrons in the graphene, confining them to a tiny energy well. When a magnetic field of 4 to 8 tesla […]
Soundwaves carry information between quantum systems
Nanowerk December 30, 2019 An international team of researchers ( USA- University of Chicago, UC Santa Barbara, Argonne National Laboratory, Japan) created a hybrid quantum system that acoustically drives transitions in electron spins. The experiment showed a basis for mechanical (strain) control. They developed a theoretical model from a combination of direct experimental observation and density functional theory calculations. From all of this information, they illustrated different types of mechanical strain that drive longer-lasting spins. The material studied was silicon carbide, which has been shown recently to support long-lived spin states that can be accessed optically. The results offer theoretical […]
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 […]
Paving the way for spintronic RAMs: A deeper look into a powerful spin phenomenon
Science Daily December 26, 2019 Extensive studies on Unidirectional spin Hall magnetoresistance (USMR) in metallic bilayers has found that its magnitude (∼10−5) is too small for practical applications. An international team of researchers(Japan,Vietnam) has demonstrated a giant USMR effect in a heterostructure of BiSb topological insulator – GaMnAs ferromagnetic semiconductors. They obtained a large USMR ratio of 1.1% and found that this giant USMR is governed not by the giant magnetoresistance like spin-dependent scattering but by magnon emission/absorption and strong spin-disorder scattering in the GaMnAs layer. Their results present a novel strategy to exploit spin-related phenomena in topological materials, which […]
Scientists discover first antiferromagnetic topological quantum material
Science Daily December 19, 2019 An international team of researchers led by Spain has developed a crystal growing technique for intrinsically magnetic topological material manganese-bismuth telluride (MnBi2Te4) and characterized the physical properties of the crystals. The team was able to prove both in theory and in spectroscopic experiments that MnBi2Te4 is the first antiferromagnetic topological insulator (AFMTI) below its Néel temperature. They optimized the synthesis protocol for the new material so that MnBi2Te4 single crystals can be produced more easily. Recent findings show that there are even more structural derivatives of MnBi2Te4, which are relevant in the context of MTI…read […]
In surprise breakthrough, scientists create quantum states in everyday electronics
Phys.org December 9, 2019 An international team of researchers (USA – University of Chicago, Argonne National Laboratory, Chicago, Japan, Sweden, Hungary) has demonstrated they could electrically control quantum states embedded in silicon carbide. The quantum states in silicon carbide have the added benefit of emitting single particles of light with a wavelength near the telecommunications band which makes them well suited to long-distance transmission through the same fiber-optic network. They found that by using the diode, a one-way switch for electrons the quantum signal suddenly became free of noise and was almost perfectly stable mitigating the impurity issue. The work […]