arXiv: Quantum Physics最新文献_第7页

Construction of Dirac spinors for electron vortex beams in background electromagnetic fields 背景电磁场中电子涡旋束狄拉克旋量的构造

arXiv: Quantum Physics Pub Date : 2020-11-25 DOI: 10.1103/PHYSREVRESEARCH.3.013245

Andre G. Campos, K. Hatsagortsyan, C. Keitel

{"title":"Construction of Dirac spinors for electron vortex beams in background electromagnetic fields","authors":"Andre G. Campos, K. Hatsagortsyan, C. Keitel","doi":"10.1103/PHYSREVRESEARCH.3.013245","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.3.013245","url":null,"abstract":"Exact solutions of the Dirac equation, a system of four partial differential equations, are rare. The vast majority of them are for highly symmetric stationary systems. Moreover, only a handful of solutions for time dependent dynamics exists. Given the growing number of applications of high energy electron beams interacting with a variety of quantum systems in laser fields, novel methods for finding exact solutions to the Dirac equation are called for. We present a method for building up solutions to the Dirac equation employing a recently introduced approach for the description of spinorial fields and their driving electromagnetic fields in terms of geometric algebras. We illustrate the method by developing several stationary as well as non-stationary solutions of the Dirac equation with well defined orbital angular momentum along the electron's propagation direction. The first set of solutions describe free electron beams in terms of Bessel functions as well as stationary solutions for both a homogeneous and an inhomogeneous magnetic field. The second set of solutions are new and involve a plane electromagnetic wave combined with a generally inhomogeneous longitudinal magnetic field. Moreover, the developed technique allows us to derive general physical properties of the dynamics in such field configurations, as well as provides physical predictions on the self-consistent electromagnetic fields induced by the dynamics.","PeriodicalId":8484,"journal":{"name":"arXiv: Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90685470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Electrons in intense laser fields with local phase, polarization, and skyrmionic textures 强激光场中的电子与局域相、极化和天空粒子织构

arXiv: Quantum Physics Pub Date : 2020-11-25 DOI: 10.1103/physreva.102.063105

J. Wätzel, J. Berakdar

引用次数: 3

Tunable and weakly invasive probing of a superconducting resonator based on electromagnetically induced transparency 基于电磁感应透明的超导谐振腔的可调谐弱侵入探测

arXiv: Quantum Physics Pub Date : 2020-11-24 DOI: 10.1103/physreva.102.053721

B. Ann, G. Steele

{"title":"Tunable and weakly invasive probing of a superconducting resonator based on electromagnetically induced transparency","authors":"B. Ann, G. Steele","doi":"10.1103/physreva.102.053721","DOIUrl":"https://doi.org/10.1103/physreva.102.053721","url":null,"abstract":"Superconducting cavities with high quality factors play an essential role in circuit quantum electrodynamics and quantum computing. In measurements of the the intrinsic loss rates of high frequency modes, it can be challenging to design an appropriate coupling to the measurement circuit in such a way that the resulting signal is sufficiently strong but also that this coupling does not lead to unwanted loading circuit, obscuring the intrinsic internal loss rates. Here, we propose and demonstrate a spectroscopic probe of high-Q resonators based on the phenomena of electromagnetically-induced transparency (EIT) between the resonator and qubit in the weak dispersive coupling regime. Applying a sideband drive signal to the qubit, we observe an interference dip originated from EIT in the qubit spectroscopy, originating from the quantum interference between the qubit probe signal and sideband transition. From the width and the depth of the dip, we are able to extract the single-photon linewidth of the resonator from an analytical model. Working in a previously unexplored regime in which the qubit has a larger linewidth than the resonator reduces the technical challenge of making a high-coherence qubit and is advantageous for remaining in the weakly-invasive limit of coupling to the resonator. Furthermore, the sideband and the dispersive coupling between the resonator and the qubit can be tuned $in~situ$ controlling the strength of the sideband drive power. This $in-situ$ tuneability allows the technique to be applied for efficient measurement of the resonator loss rate for any quality factor below a fixed upper bound, on the order of $10^8$ for our device, allowing a wide range of quality factors to probed using a single design.","PeriodicalId":8484,"journal":{"name":"arXiv: Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89714944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Effect of intersystem crossing rates and optical illumination on the polarization of nuclear spins close to nitrogen-vacancy centers 系统间交叉速率和光学光照对靠近氮空位中心的核自旋极化的影响

arXiv: Quantum Physics Pub Date : 2020-11-24 DOI: 10.1103/PhysRevB.103.195443

H. Duarte, H. T. Dinani, V. Jacques, J. Maze

{"title":"Effect of intersystem crossing rates and optical illumination on the polarization of nuclear spins close to nitrogen-vacancy centers","authors":"H. Duarte, H. T. Dinani, V. Jacques, J. Maze","doi":"10.1103/PhysRevB.103.195443","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.195443","url":null,"abstract":"Several efforts have been made to polarize the nearby nuclear environment of nitrogen vacancy (NV) centers for quantum metrology and quantum information applications. Different methods showed different nuclear spin polarization efficiencies and rely on electronic spin polarization associated to the NV center, which in turn crucially depends on the inter-system crossing. Recently, the rates involved in the inter-system crossing have been measured leading to different transition rate models. Here, we consider the effect of these rates on several nuclear polarization methods based on the level anti-crossing, and precession of the nuclear population while the electronic spin is in the ms = 0 and ms = 1 spin states. We show that the nuclear polarization depends on the power of optical excitation used to polarize the electronic spin. The degree of nuclear spin polarization is different for each transition rate model. Therefore, the results presented here are relevant for validating these models and for polarizing nuclear spins. Furthermore, we analyze the performance of each method by considering the nuclear position relative to the symmetry axis of the NV center.","PeriodicalId":8484,"journal":{"name":"arXiv: Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87581431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Single-particle steering and nonlocality: The consecutive Stern-Gerlach experiments 单粒子转向与非定域性:连续的Stern-Gerlach实验

arXiv: Quantum Physics Pub Date : 2020-11-23 DOI: 10.1103/PHYSREVA.103.042217

Beńıtez Rodŕıguez, Piceno Mart́ınez, L. A. Aguilar

{"title":"Single-particle steering and nonlocality: The consecutive Stern-Gerlach experiments","authors":"Beńıtez Rodŕıguez, Piceno Mart́ınez, L. A. Aguilar","doi":"10.1103/PHYSREVA.103.042217","DOIUrl":"https://doi.org/10.1103/PHYSREVA.103.042217","url":null,"abstract":"Quantum nonlocality and quantum steering are fundamental correlations of quantum systems which can not be created using classical resources only. Nonlocality describes the ability to influence the possible results of measurements carried out in distant systems, in quantum steering Alice remotely steers Bob's state. Research in nonlocality and steering possess a fundamental interest for the development of quantum information and in many applications requiring nonlocal resources like quantum key distribution. On the other hand, the Stern-Gerlach experiment holds an important place in the history, development and teaching of quantum mechanics and quantum information. In particular, the thought experiment of consecutive Stern-Gerlach Experiments is commonly used to exemplify the concept of non-commutativity between quantum operators. However, to the best of our knowledge, the consecutive Stern-Gerlach Experiments have not been treated in a fully quantum manner yet, and it is a widely accepted idea that atoms crossing consecutive Stern-Gerlach Experiments follow classical paths. Here we demonstrate that two consecutive Stern-Gerach Experiment generate nonlocality and steering, these nonlocal effects strongly modify our usual understanding of this experiment. Also, we discuss the implications of this result and its relation with the entanglement. This suggests the use of quantum correlations, of particles possessing mass, to generate nonlocal taks using this venerable experiment.","PeriodicalId":8484,"journal":{"name":"arXiv: Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75379691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Low-Cost Fredkin Gate with Auxiliary Space 带有辅助空间的低成本弗雷德金门

arXiv: Quantum Physics Pub Date : 2020-11-23 DOI: 10.1103/PhysRevApplied.14.054057

Wen‐Qiang Liu, Hai‐Rui Wei, L. Kwek

引用次数: 19

Interatomic interaction of two ground-state atoms in vacuum: Contributions of vacuum fluctuations and radiation reaction 真空中两个基态原子的相互作用:真空波动和辐射反应的贡献

arXiv: Quantum Physics Pub Date : 2020-11-23 DOI: 10.1103/PHYSREVA.103.012227

Wenting Zhou, Shijing Cheng, Hongwei Yu

引用次数: 5

New approach to describe two coupled spins in a variable magnetic field 描述变磁场中两个耦合自旋的新方法

arXiv: Quantum Physics Pub Date : 2020-11-23 DOI: 10.1063/5.0055009

Yuri Belousov, R. Grimaudo, A. Messina, A. Migliore, A. Sergi