Phys.org November 20, 2019 Through the interaction of the mechanical oscillator with a microwave (or optical) cavity, back-action evading measurement in principle enables noiseless measurement of the position of the mechanical oscillator. However, additional interactions between the microwave (or optical) field and the mechanical oscillator lead to instabilities in mechanical motion, which prevents continuous measurement. Through simultaneous but unequal electromechanical amplification and cooling processes, a team of researchers in the US (industry, University of Colorado, NIST) created a method for a nearly noiseless pulsed measurement of mechanical motion. The conversion of signals between these two disparate frequency bands is important […]
Tag Archives: Quantum technology
Structured light promises path to faster, more secure communications
Eurekalert November 5, 2019 Researchers in South Africa review the progress being made in using structured light in quantum protocols to create a larger encoding alphabet, stronger security and better resistance to noise. Since patterns of light can be distinguished from each other, they can be used as a form of alphabet. Its information capacity is much higher than polarized light and security is stronger, and the robustness to noise is improved. It turns out that many protocols can be efficiently implemented withotterns of light. Unfortunately, the toolkit to manage these patterns is still underdeveloped and requires a lot of […]
Researchers create blueprint for ‘quantum battery’ that doesn’t lose charge
Phys.org October 25, 2019 Researchers in Canada have provided a theoretical demonstration that creating a loss-free quantum battery is possible—offering an advantage over previously proposed quantum batteries. To realize their idea, the team considered an open quantum network model with high structural symmetry as a platform for storing excitonic energy. Using this model, they showed it is possible to store energy without any loss, despite being open to an environment. The key is to prepare this quantum network in a dark state when the network cannot exchange energy with its environment, the system becomes immune to all environmental influences. The […]
Blanket of light may give better quantum computers
Phys.org October 17, 2019 In their efforts to observe quantum phenomena on a macroscopic scale, researchers in Denmark managed to create a network of 30,000 entangled pulses of light arranged in a two-dimensional lattice distributed in space and time. They produced light beams with special quantum mechanical properties (squeezed states) and woven them together using optical fibre components to form a cluster state. An optical quantum computer will therefore not require costly and advanced refrigeration technology, its information-carrying light-based qubits in the laser light will be much more durable and it can be more easily be scaled to contain hundreds […]
Extracting hidden quantum information from a light source
Phys.org October 24, 2019 An international team of researchers (UK, USA – Princeton University) experimentally demonstrated the distillation of a quantum image from measured data composed of a superposition of both quantum and classical light. They measured the image of an object formed under quantum illumination that is mixed with another image produced by classical light with the same spectrum and polarization, and demonstrated near-perfect separation of the two superimposed images by intensity correlation measurements. This work provides a method to mix and distinguish information carried by quantum and classical light, which may be useful for quantum imaging, communications, and […]
Physicists break distance record for electron spin-state transmission in spin qubits
Physics World October 10, 2019 A team of researchers in the US (University of Rochester, Purdue University) has demonstrated coherent spin-state transfer along an array of four electrons confined in a quadruple quantum dot in a GaAs/AlGaAs heterostructure. When they applied a voltage pulse to a gate between two quantum dots, the electrons in the dots exchanged their spin states via Heisenberg exchange coupling. By applying a series of voltage pulses to specific gates, the researchers were able to shuttle the spin states of the electrons back and forth. They were able to transmit the spins of entangled electrons using […]
Tunable optical chip paves way for new quantum devices
Nanowerk October 2, 2019 Building on previous development of a platform called crystalline SiC-on-insulator researchers at Georgia Institute of Technology fabricated microring resonators, using the crystalline SiC-on-insulator technology. In each resonator, light at resonance wavelengths, traveling around the ring will build up strength through constructive interference. The resonator can be used to control the amplitude and phase of the light in a waveguide coupled to it. To create a tunable resonator with a high degree of control, they fabricated electric heaters on top of the microrings. When an electric current is applied to the integrated microheater, it locally increases the […]
This New Chip Could Bridge The Gap Between Classical And Quantum Computing
Science Alert September 28, 2019 An international team of researchers (USA – Purdue University, Japan) has developed hardware for a ‘probabilistic computer’ which solves quantum problems using a p-bit which can only be a 1 or a 0, but they can switch between those two states very quickly and p-bits work at room temperature. By carefully controlling these fluctuations, scientists can tackle calculations of a kind that are generally considered to be quantum computing problems. They modified MRAM device to present a proof-of-concept experiment for probabilistic computing. Factorization of integers up to 945 was demonstrated using eight correlated p-bits, and […]
Team closes in on ‘holy grail’ of room temperature quantum computing chips
Phys.org September 18, 2019 Researchers at the Stevens Institute of Technology have coaxed photons into interacting by firing a laser beam into a racetrack-shaped microcavity carved into a sliver of crystal. As the laser light bounces around the racetrack, its confined photons interact with one another, producing a harmonic resonance that causes some of the circulating light to change wavelength. They boosted its efficiency by using a chip made from lithium niobate on insulator. They used an ion-milling tool to etch a tiny racetrack. The team has already identified ways to increase their Q-factor by a factor of at least […]
‘Valley states’ in this super-thin material could potentially be used for quantum computing
Phys.org September 23, 2019 Past research has shown that applying a magnetic field can shift the energy of the valleys in opposite directions, lowering the energy of one valley to make it “deeper” and more attractive to electrons, while raising the energy of the other valley to make it “shallower,” A team of researchers in the US (SUNY Buffalo, University of Nebraska) showed that the shift in the energy of the two valleys can be enlarged by two orders of magnitude if we place a thin layer of magnetic europium sulfide under the tungsten disulfide. After that when they applied […]