Phys.org February 19, 2024 Researchers at the University of Colorado described a method to create and store scalable and long-lived entangled spin-squeezed states within a manifold of many-body cavity dark states using collective emission of light from multilevel atoms inside an optical cavity. They showed that the system could be tuned to generate squeezing in a dark state where it will be immune to super radiance. More generically that squeezing could be generated using a combination of super radiance and coherent driving in a bright state, and subsequently transferred via single-particle rotations to a dark state where squeezing could be […]
Category Archives: Quantum technology
Carbon-based quantum technology
Science Daily August 15, 2023 Graphene nanoribbons synthesized using bottom-up approaches can be structured with atomic precision, allowing their physical properties to be precisely controlled. For applications in quantum technology, the manipulation of single charges, spins or photons is required. However, achieving this at the level of single graphene nanoribbons is experimentally challenging due to the difficulty of contacting individual nanoribbons, particularly on-surface synthesized ones. An international team of researchers (Switzerland, UK, Germany, China) has attached electrodes to individual atomically precise nanoribbons paving the way for precise characterization of the ribbons and their possible use in quantum technology. The approach […]
A new type of quantum bit in semiconductor nanostructures
Phys.org July 25, 2023 Coherently driven semiconductor quantum dots are one of the most promising platforms for non-classical light sources and quantum logic gate. However, coherent manipulation of single charge carriers in quantum dots is limited mainly to their lowest orbital states. Ultrafast coherent control of high-orbital states is obstructed by the demand for tunable terahertz pulses. An international team of researchers (UK, Germany, China) demonstrated an all-optical method to control high-orbital states of a hole via a stimulated Auger process. The coherent nature of the Auger process was proved by Rabi oscillation and Ramsey interference. Harnessing this coherence further […]
Study offers a broader approach to quantum walks
Phys.org July 14, 2023 Quantum walks have been widely studied for their ability to simulate a wide range of transport phenomena. Physicists have previously studied two distinct types of quantum walk, but so far, they haven’t widely considered how their mathematical descriptions could be linked. They have long been considered the discrete-time and discrete space analogue of the Dirac equation and have been used as a primitive to simulate quantum field theories precisely because of some of their internal symmetries. Researchers in France have introduced a new family of quantum walks, a more general family named “twisted” quantum walkers, named […]
Finding the flux of quantum technology
Science Daily July 5, 2023 Researchers at the University of Pittsburgh showed that a circularly polarized electric dipole harbors a near-field concentrated wave which orbits around with an energy flux five orders of magnitude larger than far-field radiation. The near-field wave was found to carry transverse spins and reveal skyrmion spin texture. By performing electromagnetic analysis and numerical simulation, they demonstrated chiral extraction of a near-field rotational energy flux: the confined energy flow was out-coupled to surface plasmons on metal surface, whose curvature was designed to provide orbital angular momentum matched to spin angular momentum of dipole field, that is, […]
Trillionths of a second: Photon pairs compress an electron beam into short pulses
Phys.org June 19, 2023 Researchers in Germany used nonlinear-optical two-photon transitions for the quantum-coherent control of a free-electron matter wave in free space. They superimposed an electron beam with two crossed laser beams of different photon energies for non-linear Compton scattering. At suitable angle combinations, the electron energy spectrum became modulated into discrete energy sidebands with thousands of interference maxima. They explained their observations by the cascaded addition and subtraction of two-photon pairs under three-body conservation of energy and momentum. Calculations revealed that the electron matter wave converted into pulses of few-attosecond duration. According to the researchers their work provides […]
The ‘breath’ between atoms — a new building block for quantum technology
Science Daily June 1, 2023 Quantum light sources in which coupling between single photons and phonons can be controlled and harnessed enables quantum information transduction. Researchers at the University of Washington created quantum emitters featuring highly tunable coupling between excitons and phonons. The quantum emitters were formed in strain-induced quantum dots created in homobilayer WSe2. The colocalization of quantum-confined interlayer excitons and terahertz interlayer breathing-mode phonons, which directly modulated the exciton energy, led to a uniquely strong phonon coupling to single-photon emission. Due to the vertical dipole moment of the interlayer exciton, the phonon–photon interaction was electrically tunable to be […]
Wiring up quantum circuits with light
Science Daily May 18, 2023 Quantum entanglement is a key resource in currently developed quantum technologies. Sharing this fragile property between superconducting microwave circuits and optical or atomic systems would enable new functionalities, but this has been hindered by an energy scale mismatch of >104 and the resulting mutually imposed loss and noise. Researchers in Austria created and verified entanglement between microwave and optical fields in a millikelvin environment. Using an optically pulsed superconducting electro-optical device, they showed entanglement between propagating microwave and optical fields in the continuous variable domain. According to the researchers their work not only paves the […]
Two qudits fully entangled
Science Daily April 20, 2023 Quantum information carriers, just like most physical systems, naturally occupy high-dimensional Hilbert spaces. Instead of restricting them to a two-level subspace, these high-dimensional (qudit) quantum systems are emerging as a powerful resource for the next generation of quantum processors. Yet harnessing the potential of these systems requires efficient ways of generating the desired interaction between them. Researchers in Austria experimentally demonstrated implementation of a native two-qudit entangling gate up to dimension 5 in a trapped-ion system. This was achieved by generalizing a recently proposed light-shift gate mechanism to generate genuine qudit entanglement in a single […]
The quantum twisting microscope: A new lens on quantum materials
Science Daily February 23, 2023 An international team of researchers (Israel, Japan) developed and demonstrated conceptually, a new type of tool — the quantum twisting microscope (QTM) — that could create novel quantum materials while simultaneously gazing into the most fundamental quantum nature of their electrons. It is capable of performing local interference experiments at its tip. The QTM is based on a unique van der Waals tip, allowing the creation of pristine two-dimensional junctions, which provide a multitude of coherently interfering paths for an electron to tunnel into a sample. With the addition of a continuously scanned twist angle […]