Science Daily November 20, 2020 Controlling interaction between quantum dots could greatly improve charge transport, leading to more efficient solar cells. Researchers fabricated CdTe quantum dot superlattices via the layer-by-layer assembly of positively charged polyelectrolytes and negatively charged CdTe quantum dots to control the dimension of the quantum resonance by independently changing the distances between quantum dots in the stacking (out-of-plane) and in-plane directions. They experimentally verified the miniband formation. The fabrication method can be used with other types of water-soluble quantum dots and nanoparticles. Combining different types of semiconductor quantum dots, or combining semiconductor quantum dots with other nanoparticles, […]
Tag Archives: Quantum technology
This Weird, Cheap Quantum Device Can Run For a Year With a Single Kick of Energy
Science Alert November 22, 2020 Continuous, battery-free operation of sensor nodes requires ultra-low-power sensing and data-logging techniques. According to the researchers at Washington University by directly coupling a sensor/transducer signal into globally asymptotically stable monotonic dynamical systems based on Fowler-Nordheim quantum tunneling, it is possible to achieve self-powered sensing at an energy budget that is currently unachievable using conventional energy harvesting methods. They have developed a device that uses a differential architecture to compensate for environmental variations and the device can retain sensed information for durations ranging from hours to days. With a theoretical operating energy budget less than 10 […]
Analysis paves way for more sensitive quantum sensors
Nanowerk November 16, 2020 Researchers at the University of Chicago proposed creating a string of photonic cavities, where photons can be transported to adjacent cavities. Such a string could be used as a quantum sensor. By harnessing non-Hermitian dynamics, where dissipation leads to interesting consequences, they were able to calculate that a string of these cavities would increase the sensitivity of the sensor much more than the number of cavities added. In fact, it would increase the sensitivity exponentially in system size. To prove the theory, they are building a network of superconducting circuits that can move photons between cavities. […]
Tiny device enables new record in super-fast quantum light detection
EurekAlert November 9, 2020 An international team of researchers (UK, France) has made a new miniaturized device by interfacing CMOS-compatible silicon and germanium-on-silicon nanophotonics with silicon-germanium integrated amplification electronics. The detector has a 3 dB bandwidth of 1.7 GHz, is shot noise limited to 9 GHz and has a miniaturized required footprint of 0.84 mm2. The detector can measure the continuous spectrum of squeezing from 100 MHz to 9 GHz of a broadband squeezed light source pumped with a continuous-wave laser. The research provides fast, multipurpose, homodyne detectors for continuous-variable quantum optics, and opens the way to full-stack integration of photonic quantum devices…read more. TECHNICAL ARTICLE
Breakthrough quantum-dot transistors create a flexible alternative to conventional electronics
Science Daily October 29, 2020 So far, most research on quantum dot electronic devices has focused on materials based on Pb- and Cd chalcogenides. In addition to environmental concerns associated with the presence of toxic metals, these quantum dots are not well suited for applications in CMOS circuits due to difficulties in integrating complementary n- and p-channel transistors in a common quantum dot active layer. A team of researchers in the US (Los Alamos National Laboratory, UC Irvine) demonstrated that by using heavy-metal-free CuInSe2 quantum dots, they could address the problem of toxicity and simultaneously achieve straightforward integration of complimentary […]
Physicists develop efficient modem for a future quantum internet
Phys.org November 5, 2020 A central research object is the interface between local quantum devices and light quanta that enable the remote transmission of highly sensitive quantum information. Researchers in Germany integrated a thin crystal of erbium-doped yttrium orthosilicate a cryogenic Fabry-Perot resonator leading to 56-fold enhancement of the emission rate with an out-coupling efficiency of 46%. They demonstrated that the emitter properties are not degraded. They observed ensemble-averaged optical coherence up to 0.54 ms, which exceeds the 0.19 ms lifetime of dopants at the cavity field maximum. The approach is also applicable to other solid-state quantum emitters, such as […]
Optical wiring for large quantum computers
Phy.org October 22, 2020 The fundamental qualities of individual trapped-ion qubits are promising for long-term systems, but the optics involved in their precise control are a barrier to scaling. Researchers in Switzerland used scalable optics co-fabricated with a surface-electrode ion trap to achieve high-fidelity multi-ion quantum logic gates, which are often the limiting elements in building up the precise, large-scale entanglement that is essential to quantum computation. Light is efficiently delivered to a trap chip in a cryogenic environment via direct fibre coupling on multiple channels, eliminating the need for beam alignment into vacuum systems and cryostats and lending robustness […]
An 11-atom sensor sheds light on the quantum world
Nanowerk October 14, 2020 Researchers in the Netherlands developed a device composed of individual Fe atoms that allows for remote detection of spin dynamics. They have characterized the device and used it to detect the presence of spin waves originating from an excitation induced by the scanning tunneling microscope tip several nanometres away; this may be extended to much longer distances. The device contains a memory element that can be consulted seconds after detection, similar in functionality to e.g. a single photon detector. They performed statistical analysis of the responsiveness to remote spin excitations and corroborated the results using basic […]
A milestone in quantum physics: Physicists successfully carry out the controlled transport of stored light
Nanowerk October 13, 2020 Quantum memories for light, realized with cold atomic samples as the storage medium, are prominent for their high storage efficiencies and lifetime. Researchers in Germany used ultra-cold rubidium-87 atoms as a storage medium for the light as to achieve a high level of storage efficiency and a long lifetime. They transported the stored light over 1.2 mm. They showed that the transport process and its dynamics only have a minor effect on the coherence of the storage. Extending the presented concept to longer transport distances and augmenting the number of storage sections will allow for the […]
New quantum computing algorithm skips past time limits imposed by decoherence
Phys.org October 5, 2020 An international team of researchers (USA – Los Alamos National Laboratory, industry, UK) has developed a hybrid quantum-classical algorithm, called variational fast forwarding (VFF) which is a hybrid combining aspects of classical and quantum computing. Although well-established theorems exclude the potential of general fast forwarding with absolute fidelity for arbitrary quantum simulations, the researchers get around the problem by tolerating small calculation errors for intermediate times to provide useful, if slightly imperfect, predictions. The errors that build up as simulation times increase limits potential calculations. Still, the algorithm allows simulations far beyond the time scales that […]