Science Daily November 16, 2020 A team of researchers in the US (Western Washington University, UC Santa Barbara, University of Michigan, NYCity University) has developed a quantum algorithm that uses quantum gates acting on neighboring qubits in a quasi-one-dimensional setting and its circuit depth is linear in the number of qubits. They identified correlation functions that serve as signatures of the Laughlin state and discussed how to obtain them on a quantum computer. Application of the algorithm provides tools to improve quantum computing devices. The algorithm opens a new venue to use the new quantum devices to study problems which […]
Tag Archives: Quantum science
‘Classified knots’: Researchers create optical framed knots to encode information
Phys.org October 17, 2020 Modern beam shaping techniques have enabled the generation of optical fields displaying a wealth of structural features. Due to their robustness against external perturbations, topological invariants in physical systems are increasingly being considered to encode information. Hence, structured light with topological properties could potentially be used for such purposes. An international team of researchers (Canada, USA – MIT, Israel) has experimentally demonstrated structures known as framed knots within optical polarization fields. They developed a protocol in which the topological properties of framed knots are used in conjunction with prime factorization to encode information…read more. Open Access […]
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 […]
An electrical trigger fires single, identical photons
Phys.org October 8, 2020 An international team of researchers (USA – Lawrence Berkeley National Laboratory, Montana State University, Spain) has demonstrated electrically stimulated photon emission from individual atomic defects in monolayer WS2 and directly correlated the emission with the local atomic and electronic structure. Radiative transitions are locally excited by sequential inelastic electron tunneling from a metallic tip into selected discrete defect states in the WS2 bandgap. Coupling to the optical far field is mediated by tip plasmons, which transduce the excess energy into a single photon. The applied tip-sample voltage determines the transition energy. Inelastic charge carrier injection into […]
Quantum entanglement realized between distant large objects
Phys.org September 28, 2020 The disparity of hybrid systems and the vulnerability of quantum correlations have thus far hampered the generation of macroscopic hybrid entanglement. An international team of researchers (Spain, USA – University of Chicago, Denmark) generated an entangled state between the motion of a macroscopic mechanical oscillator and a collective atomic spin oscillator, as witnessed by an Einstein–Podolsky–Rosen variance below the separability limit, 0.83 ± 0.02 < 1. The mechanical oscillator is a millimetre-size dielectric membrane, and the spin oscillator is an ensemble of 109 atoms in a magnetic field. Light propagating through the two spatially separated systems […]
First ever observation of ‘time crystals’ interacting
EurekAlert August 17, 2020 Protecting coherence is the main difficulty hindering the development of powerful quantum computers. An international team of researchers (Finland, UK, USA – Yale University, Russia) cooled superfluid helium-3 to within one ten thousandth of a degree from absolute zero and created two time crystals inside the superfluid. They observed an exchange of magnons between the time crystals leading to opposite-phase oscillations leading to opposite-phase oscillations in their populations while the defining periodic motion remains phase coherent throughout the experiment. The findings offer a basis to further investigate the fundamental properties of these phases, opening pathways for […]
Ultrafast electrons in magnetic oxides: A new direction for spintronics?
Science Daily August 19, 2020 Special metal oxides could one day replace semiconductor materials that are commonly used today in processors. Until recently it had not been clear how the electron transfer across the band gap coupled with the spin of the magnetic oxide occurs. An international team of researchers (Germany, USA – research institute, Switzerland) was able to excite an electron to lift it across the band gap in nickel oxide. They also observed how the information was then transferred to the magnetic system. This enabled the team to identify a previously unknown ultrafast coupling mechanism that occurs on […]