A quantum of solid

Science Daily  January 30, 2020 Quantum control of complex objects in the regime of large size and mass provides opportunities for sensing applications and tests of fundamental physics. An international team of researchers (Austria, MIT) has demonstrated a quantum interface that combines optical trapping of solids with cavity-mediated light matter interaction. Precise control over the frequency and position of the trap laser with respect to the optical cavity allows laser-cooling an optically trapped nanoparticle into its quantum ground state of motion from room temperature. The cooling, in combination with optical trap manipulation, may enable otherwise unachievable superposition states involving large […]

The experimental demonstration of a spin quantum heat engine

Phys.org  December 30, 2019 An international team of researchers (Canada, Singapore, Brazil) successfully demonstrated that the proof-of-concept quantum heat engine is able to reach an efficiency for work extraction very close to its thermodynamic limit. They used a nuclear spin placed in a chloroform molecule and nuclear magnetic resonance techniques. They specifically manipulated the nuclear spin of a Carbon 13 isotope using a radiofrequency field, ultimately producing an Otto cycle (i.e., the thermodynamic cycle used in most common motors). They were able to characterize all energy fluctuations in work and heat, besides the irreversibility at the quantum scale…read more. TECHNICAL […]

Structured light promises path to faster, more secure communications

Science Daily  October 29, 2019 Researchers in South Africa review the recent progress in the emergence of a second quantum revolution ushering in control of quantum states, outlining the core concepts in a tutorial manner before delving into the advances made in creation, manipulation, and detection of such quantum states. They cover advances in using orbital angular momentum as well as vectoral states that are hybrid entangled, combining spatial modes with polarization to form an infinite set of two-dimensional spaces: multidimensional entanglement. The authors highlight the work in pushing the boundaries in both the dimension and the photon number, before […]

Physicists couple key components of quantum technologies

EurekAlert  October 9, 2019 Researchers in Germany developed an interface that couples light sources for single photons with nanophotonic networks. They considered quantum emitters which are embedded in nanodiamonds and emit photons when they are stimulated by means of electromagnetic fields. In order to produce the desired interfaces, they aimed to develop optical structures tailored to the wavelength of the quantum emitters. In structuring the crystals, they varied not only the size and the arrangement of the cavities, but also the width of the waveguide on which the cavities were placed. They found photonic crystals which demonstrated a special variation […]

Creating different kinds of light with manipulable quantum properties

Science Daily  September 27, 2019 An international team of researchers (Louisiana State University, NIST, Mexico, Germany) experimentally demonstrated that the manipulation of the quantum electromagnetic fluctuations of two-mode squeezed vacuum states leads to a family of quantum-correlated multiphoton states with tunable mean photon numbers and degree of correlation. The technique relies on the use of conditional measurements to engineer the excitation mode of the field through the simultaneous subtraction of photons from two-mode squeezed vacuum states. They demonstrated the engineering of a quantum state of light with up to ten photons which is an important step towards the generation of […]

Entangling photons generated millions of miles apart

Phys.org  August 28, 2019 An international team of researchers (China, USA – Louisiana State University, Texas A&M University, Baylor University, Princeton University, Germany, UK) conducted an experiment to test quantum interference, entanglement, and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by approximately 150 million km. By making the photons indistinguishable in all degrees of freedom, they observed time-resolved two-photon quantum interference with a raw visibility of 0.796, well above the 0.5 classical limit, providing unambiguous evidence of the quantum nature of thermal light. Using the photons with no […]

Switching electron properties on and off individually

Science Daily  August 22, 2019 An international team of researchers (Austria, USA – Rice University, University of Florida, Germany) investigated a material made of palladium, silicon and cerium focusing on the electrons located at the cerium atom and on the conduction electrons, which can move freely through the crystal. The conduction electrons can virtually hide both the spin and the orbital state of the fixed electrons. This means that order is no longer possible. They have developed a system in which the order can be switched on and off individually in relation to two different degrees of freedom that are […]

Quantum light sources pave the way for optical circuits

Science Daily  August 1, 2019 The ability to tailor quantum emitters via site-selective defect engineering is essential for realizing scalable architectures. However, a major difficulty is that defects need to be controllably positioned within the material. An international team of researchers (Germany, USA – SUNY Buffalo, Japan) has overcome this challenge by controllably irradiating monolayer MoS2 using a sub-nm focused helium ion beam to deterministically create defects. Subsequent encapsulation of the ion exposed MoS2 flake with high-quality hBN reveals spectrally narrow emission lines that produce photons in the visible spectral range. The new method allows for a multitude of applications in […]

Physicists find first possible 3-D quantum spin liquid

Phys.org  July 15, 2019 A quantum spin liquid is a state of matter where unpaired electrons’ spins, although entangled, do not show magnetic order even at the zero temperature. An international team of researchers (USA – Rice University, UC San Diego, Oak Ridge National Laboratory, Rutgers University, industry, UK, Switzerland, South Korea, University of Hong Kong) used thermodynamic, muon spin relaxation and neutron scattering experiments on single crystals of Ce2Zr2O7 to demonstrate the absence of magnetic ordering and the presence of a spin excitation continuum at 35 mK. With no evidence of oxygen deficiency and magnetic/non-magnetic ion disorder seen by neutron […]

‘Connecting the dots’ for quantum networks

Science Daily  July 9, 2019 For quantum dots to “communicate”, they must emit light at the same wavelength. The size of a quantum dot determines this emission wavelength. Instead of making quantum dots perfectly identical to begin with, researchers at the US Naval Research Laboratory change their wavelength afterwards by shrink-wrapping them with laser-crystallized hafnium oxide, squeezing the quantum dots, which shifts their wavelength in a very controllable way. Doing this for many quantum dots in an integrated circuit, could be used for optical, rather than electrical computing. The technique could accelerate the development of quantum information technologies and brain-inspired […]