Phys.org September 23, 2020 An international team of researchers (China, Japan, Germany) developed a novel type of quantum emitter formed from spatially separated monolayer islands of InGaN sandwiched in a GaN matrix. They first grew a planar structure of InGaN monolayer islands using molecular beam epitaxy, and then patterned the sample into pillars using nanoimprint lithography and inductively-coupled plasma reactive-ion etching. Detailed optical analysis of the emission properties of the isolated monolayer islands showed that the main emission line could be spectrally filtered to act as a bright, and fast single photon emitter at a wavelength of ~ 400 nm, […]
Tag Archives: Quantum technology
Quantum light squeezes the noise out of microscopy signals
Phys.org September 8, 2020 A team of researchers in the US (Tulane University, MIT, University of Colorado) demonstrated the first practical application of nonlinear interferometry by measuring the displacement of an atomic force microscope microcantilever with quantum noise reduction of up to 3 dB below the standard quantum limit, corresponding to a quantum-enhanced measurement of beam displacement. They minimized photon backaction noise while taking advantage of quantum noise reduction by transducing the cantilever displacement signal with a weak squeezed state while using dual homodyne detection with a higher power local oscillator. This approach may enable quantum-enhanced broadband, high-speed scanning probe […]
Tiny bubbles make a quantum leap
EurekAlert July 13, 2020 An international team of researchers (USA – UC Berkeley, Columbia University, industry, Montana State University, Germany, Japan) found that placing sufficient strain in a 2D material–tungsten diselenide creates localized states that can yield single-photon emitters. The team was able to directly image these states for the first time, revealing that even at room temperature they are highly tunable and act as quantum dots, tightly confined pieces of semiconductors that emit light. Fully tunable, room-temperature single-photon emitters are now within our grasp, paving the way for controllable–and practical quantum photonic devices. These devices can be the foundation […]
‘Hot and messy’ entanglement of 15 trillion atoms
Nanowerk May 15, 2020 Quantum technologies often employ strong cooling and isolation to protect entangled entities from decoherence by random interactions. Researchers in Spain heated a collection of atoms to 450 Kelvin. The individual atoms collided with each other every few microseconds, and each collision set their electrons spinning in random directions. They observed an enormous number of entangled atoms – about 100 times more than ever before observed. The entanglement is non-local and the entanglement remains for about 1 millisecond, which means that 1000 times per second a new batch of 15 trillion atoms is being entangled. This clearly […]
Scientists demonstrate quantum radar prototype
Science Daily May 8, 2020 Instead of using conventional microwaves, an international team of researchers (Austria, UK. USA – MIT, Italy) entangled two groups of photons, which are called the ‘signal’ and ‘idler’ photons. The ‘signal’ photons are sent out towards the object of interest, whilst the ‘idler’ photons are measured in relative isolation, free from interference and noise. When the signal photons are reflected back, true entanglement between the signal and idler photons is lost, but a small amount of correlation survives, creating a signature or pattern that describes the existence or the absence of the target object — […]
Molecules with a spin on a topological insulator: a hybrid approach to magnetic topological states of matter
Nanowerk April 29, 2020 Controlling the interactions at the interface of a magnetic/topological insulator heterostructure is an outstanding challenge with implications in fundamental science and technology. An international team of researchers (Spain, Switzerland, Italy) has shown that it is possible to tune the interfacial interaction without quenching the molecular spin and the topological surface state of the topological insulator by choosing suitable organic ligands. They found that CoTBrPP and CoPc monolayers (metal-organic molecules) adsorbed on Bi2Te3 (topological insulator) form robust interfaces where electronic interactions can be tuned without strongly perturbing the intrinsic properties of each constituent. Their conclusions are supported […]
Quantum entanglement offers unprecedented precision for GPS, imaging and beyond
Science Daily April 20, 2020 To date, almost all quantum-metrology demonstrations are restricted to improving the measurement performance at a single sensor. A team of researchers in the US (University of Arizona, industry) has demonstrated an entangled sensor network, empowered by continuous-variable (CV) multipartite entanglement, which is composed of three sensor nodes each equipped with an electro-optic transducer for the detection of radio-frequency (RF) signals. By properly tailoring the CV multipartite entangled states, the network can be reconfigured to maximize the quantum advantage in distributed RF sensing problems such as measuring the angle of arrival of an RF field. The […]
Wiring the quantum computer of the future: A novel simple build with existing technology
Phys.org April 23, 2020 A major hurdle for the scalability in quantum error-correction architecture using superconducting systems is the wiring problem, where qubits internal to a chipset become difficult to access by the external control/readout lines. An international team of researchers (Japan, Australia) carried out experiments to examine the feasibility of the new airbridge component whose measured quality factor of the airbridged resonator is below the simulated surface-code threshold required for a coupling resonator and not limit simulated gate fidelity. The measured crosstalk between crossed resonators is at most −49 dB in resonance. The spatial and frequency separation between the […]
A spookily good sensor
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 […]
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 […]