Cool atoms for quantum technology

2020 ◽  
Author(s):  
Peter L. Knight
Keyword(s):  
Quantum Technology

scholarly journals Quantum Reinforcement Learning with Quantum Photonics

Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 33
Author(s):  
Lucas Lamata
Keyword(s):  
Machine Learning ◽  
Reinforcement Learning ◽  
Quantum Computation ◽  
Exchange Information ◽  
Quantum Machine Learning ◽  
Quantum Technology ◽  
Quantum Photonics

Quantum machine learning has emerged as a promising paradigm that could accelerate machine learning calculations. Inside this field, quantum reinforcement learning aims at designing and building quantum agents that may exchange information with their environment and adapt to it, with the aim of achieving some goal. Different quantum platforms have been considered for quantum machine learning and specifically for quantum reinforcement learning. Here, we review the field of quantum reinforcement learning and its implementation with quantum photonics. This quantum technology may enhance quantum computation and communication, as well as machine learning, via the fruitful marriage between these previously unrelated fields.

scholarly journals Visualizing atomic structure and magnetism of 2D magnetic insulators via tunneling through graphene

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhizhan Qiu ◽  
Matthew Holwill ◽  
Thomas Olsen ◽  
Pin Lyu ◽  
Jing Li ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Deep Understanding ◽  
Magnetic Coupling ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Electronic And Magnetic Properties ◽  
Conducting Path ◽  
Magnetic Insulators ◽  
Quantum Technology

AbstractThe discovery of two-dimensional (2D) magnetism combined with van der Waals (vdW) heterostructure engineering offers unprecedented opportunities for creating artificial magnetic structures with non-trivial magnetic textures. Further progress hinges on deep understanding of electronic and magnetic properties of 2D magnets at the atomic scale. Although local electronic properties can be probed by scanning tunneling microscopy/spectroscopy (STM/STS), its application to investigate 2D magnetic insulators remains elusive due to absence of a conducting path and their extreme air sensitivity. Here we demonstrate that few-layer CrI3 (FL-CrI3) covered by graphene can be characterized electronically and magnetically via STM by exploiting the transparency of graphene to tunneling electrons. STS reveals electronic structures of FL-CrI3 including flat bands responsible for its magnetic state. AFM-to-FM transition of FL-CrI3 can be visualized through the magnetic field dependent moiré contrast in the dI/dV maps due to a change of the electronic hybridization between graphene and spin-polarised CrI3 bands with different interlayer magnetic coupling. Our findings provide a general route to probe atomic-scale electronic and magnetic properties of 2D magnetic insulators for future spintronics and quantum technology applications.

scholarly journals Decoherence dynamics estimation for superconducting gate-model quantum computers

2020 ◽  
Vol 19 (10) ◽  
Author(s):  
Laszlo Gyongyosi
Keyword(s):  
Gaussian Noise ◽  
Quantum Computer ◽  
Computer Architectures ◽  
Quantum Circuits ◽  
Optimal Placement ◽  
Quantum Computers ◽  
Intermediate Scale ◽  
Layout Generation ◽  
Quantum Technology ◽  
Physical Layout

Abstract Superconducting gate-model quantum computer architectures provide an implementable model for practical quantum computations in the NISQ (noisy intermediate scale quantum) technology era. Due to hardware restrictions and decoherence, generating the physical layout of the quantum circuits of a gate-model quantum computer is a challenge. Here, we define a method for layout generation with a decoherence dynamics estimation in superconducting gate-model quantum computers. We propose an algorithm for the optimal placement of the quantum computational blocks of gate-model quantum circuits. We study the effects of capacitance interference on the distribution of the Gaussian noise in the Josephson energy.

scholarly journals A variational toolbox for quantum multi-parameter estimation

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Johannes Jakob Meyer ◽  
Johannes Borregaard ◽  
Jens Eisert
Keyword(s):  
Parameter Estimation ◽  
Information Science ◽  
Quantum Algorithms ◽  
Continuous Variable ◽  
General Interest ◽  
Quantum Metrology ◽  
Estimation Problems ◽  
General Parameter ◽  
Quantum Technology ◽  
Aided Design

AbstractWith an ever-expanding ecosystem of noisy and intermediate-scale quantum devices, exploring their possible applications is a rapidly growing field of quantum information science. In this work, we demonstrate that variational quantum algorithms feasible on such devices address a challenge central to the field of quantum metrology: The identification of near-optimal probes and measurement operators for noisy multi-parameter estimation problems. We first introduce a general framework that allows for sequential updates of variational parameters to improve probe states and measurements and is widely applicable to both discrete and continuous-variable settings. We then demonstrate the practical functioning of the approach through numerical simulations, showcasing how tailored probes and measurements improve over standard methods in the noisy regime. Along the way, we prove the validity of a general parameter-shift rule for noisy evolutions, expected to be of general interest in variational quantum algorithms. In our approach, we advocate the mindset of quantum-aided design, exploiting quantum technology to learn close to optimal, experimentally feasible quantum metrology protocols.

scholarly journals A perspective on high photon flux nonclassical light and applications in nonlinear optics

2020 ◽  
Vol 8 ◽  
Author(s):  
Th. Lamprou ◽  
I. Liontos ◽  
N. C. Papadakis ◽  
P. Tzallas
Keyword(s):  
Nonlinear Optics ◽  
Quantum Optics ◽  
Vital Role ◽  
Photon Flux ◽  
Light Sources ◽  
Future Prospects ◽  
Nonclassical Light ◽  
Low Intensity ◽  
High Photon Flux ◽  
Quantum Technology

Abstract Nonclassical light sources have a vital role in quantum optics as they offer a unique resource for studies in quantum technology. However, their applicability is restricted by their low intensity, while the development of new schemes producing intense nonclassical light is a challenging task. In this perspective article, we discuss potential schemes that could be used towards the development of high photon flux nonclassical light sources and their future prospects in nonlinear optics.

Quadrature entanglement in the microwave domain with a phase locking protocol

2021 ◽  
Author(s):  
Tianli Wei ◽  
Dewei Wu ◽  
Qiang Miao ◽  
Chunyan Yang
Keyword(s):  
Relative Phase ◽  
Phase Locking ◽  
Error Signal ◽  
Parametric Amplifiers ◽  
Theoretical Derivation ◽  
Entanglement Generation ◽  
The Past ◽  
Potential Applications ◽  
Locking Protocol ◽  
Quantum Technology

Abstract Entanglement has attracted great attention in the past few decades due to its potential applications in the field of quantum information protocols. From now, achieving excellent phase locking in entanglement generation is significant yet a challenging task in cryogenic quantum technology. In this work, we propose and demonstrate a comprehensive paradigm of phase locking protocol for quadrature entanglement at the microwave wavelengths. We carry out a theoretical derivation of the quadrature entangled microwaves generated based on Josephson Parametric Amplifiers (JPAs), and the phase locking error signal, which is used to lock the relative phase of zero between the two quadrature squeezed microwaves. Simulating data for the phase locking scheme are shown under different parameter settings for comparison. Finally, we use the proposed phase locking scheme to enable a stable output of quadrature entangled microwave.

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