Long-distance quantum communication and networking require quantum memory nodes with efficient optical interfaces and long memory times. We report the realization of an integrated two-qubit network node based on silicon-vacancy centers (SiVs) in diamond nanophotonic cavities. Our qubit register consists of the SiV electron spin acting as a communication qubit and the strongly coupled silicon-29 nuclear spin acting as a memory qubit with a quantum memory time exceeding 2 seconds. By using a highly strained SiV, we realize electron-photon entangling gates at temperatures up to 1.5 kelvin and nucleus-photon entangling gates up to 4.3 kelvin. We also demonstrate efficient error detection in nuclear spin–photon gates by using the electron spin as a flag qubit, making this platform a promising candidate for scalable quantum repeaters.
An efficient, scalable source of shaped single photons that can be directly integrated with optical fiber networks and quantum memories is at the heart of many protocols in quantum information science. We demonstrate a deterministic source of arbitrarily temporally shaped single-photon pulses with high efficiency [detection efficiency ¼ 14.9%] and purity [g ð2Þ ð0Þ ¼ 0.0168] and streams of up to 11 consecutively detected single photons using a silicon-vacancy center in a highly directional fiberintegrated diamond nanophotonic cavity. Combined with previously demonstrated spin-photon entangling gates, this system enables on-demand generation of streams of correlated photons such as cluster states and could be used as a resource for robust transmission and processing of quantum information.
2The empirical development of the dynamical theory of heat or classical equilibrium thermodynamics as we know it, was only possible because of the definition through a phenomenological approach of two fundamental physical concepts, which are the actual pillars of the theory: energy and entropy [1]. It is with these two concepts that the laws (or principles) of thermodynamics could be stated and the absolute temperature be given a first proper definition. Though energy remains as fully enigmatic as entropy from the ontological viewpoint, the latter concept is not completely understood from the physical viewpoint. This of course did not preclude the success of equilibrium thermodynamics as evidenced not only by the development of thermal sciences and engineering, but also because of its cognate fields that owe it, at least partly or as an indirect consequence, their birth, from quantum physics to information theory.Early attempts to refine and give thermodynamics solid grounds started with the development of the kinetic theory of gases and of statistical physics, which in turn permitted studies of irreversible processes with the development of nonequilibrium thermodynamics [2-5] and later on finite-time thermodynamics [6,7] thus establishing closer ties between the concrete notion of irreversibility and the more abstract entropy, notably with Boltzmann's statistical definition [8] and Gibbs' ensemble theory [9]. Notwithstanding conceptual difficulties inherent to the foundations of statistical physics such as, e.g., irreversibility and the ergodic hypothesis [10,11], entropy acquired a meaningful statistical character and the scope of its definitions could be extended beyond thermodynamics, thus paving the way to information theory, as information content became a physical quantity per se, i.e. something that can be measured [12]. And, while quantum physics developed independently from thermodynamics, it extended the scope of statistical physics with the introduction of quantum statistics, led to the definition of the von Neumann entropy [13], and also introduced new problems related to small, i.e. mesoscopic and nanoscopic, systems [14,15], down to nuclear matter [16], where the concepts of thermodynamic limit and ensuing standard definitions of thermodynamic quantities may be put at odds.Quantum physics problems that overlap with thermodynamics, are typically classified into different categories: ground state characterization [17], thermal state characterization at finite temperature [18], calculation of the dynamics of either closed or open systems [19,20], state reconstruction from tomographic data [21], and quantum system control, which, given the complexity for its implementation, requires the development of new methods [22]. There are essentially two large families of techniques applicable to such problems: One is based on the quantum Monte Carlo (QMC) framework [23], which is powerful to overcome the curse of dimensionality by using the stochastic estimation of high-dimensional integrals; the other family e...
No abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.