Cavity-Enhanced Atom-Photon Entanglement with Subsecond Lifetime
02 Mar 2021-Physical Review Letters (American Physical Society (APS))-Vol. 126, Iss: 9, pp 090501-090501
TL;DR: In this article, dual control modes in a ring cavity were used to create entanglement between an atomic ensemble and a single photon with subsecond lifetime and high efficiency, and the memory efficiency was 38% for 0.1 s storage.
Abstract: A cold atomic ensemble suits well for optical quantum memories, and its entanglement with a single photon forms the building block for quantum networks that give promise for many revolutionary applications. Efficiency and lifetime are among the most important figures of merit for a memory. In this Letter, we report the realization of entanglement between an atomic ensemble and a single photon with subsecond lifetime and high efficiency. We engineer dual control modes in a ring cavity to create entanglement and make use of three-dimensional optical lattice to prolong memory lifetime. The memory efficiency is 38% for 0.1 s storage. We verify the atom-photon entanglement after 1 s storage by testing the Bell inequality with a result of $S=2.36\ifmmode\pm\else\textpm\fi{}0.14$.
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TL;DR: In this article , the authors reported the establishment of postselected entanglement between two atomic quantum memories physically separated by 12.5 km by making use of frequency downconversion and up-conversion.
Abstract: Quantum internet gives the promise of getting all quantum resources connected, and it will enable applications far beyond a localized scenario. A prototype is a network of quantum memories that are entangled and well separated. In this Letter, we report the establishment of postselected entanglement between two atomic quantum memories physically separated by 12.5 km directly. We create atom-photon entanglement in one node and send the photon to a second node for storage via electromagnetically induced transparency. We harness low-loss transmission through a field-deployed fiber of 20.5 km by making use of frequency down-conversion and up-conversion. The final memory-memory entanglement is verified to have a fidelity of 90% via retrieving to photons. Our experiment makes a significant step forward toward the realization of a practical metropolitan-scale quantum network.
16 citations
TL;DR: In this article , the authors exploit the full spectral information of the optical field in order to beat the Rayleigh limit in spectroscopy, using an optical quantum memory with spin-wave storage and an embedded processing capability to implement a time-inversion interferometer for input light.
Abstract: Existing super-resolution methods of optical imaging hold a solid place as an application in natural sciences, but many new developments allow for beating the diffraction limit in a more subtle way. One of the recently explored strategies to fully exploit information already present in the field is to perform a quantum-inspired tailored measurements. Here we exploit the full spectral information of the optical field in order to beat the Rayleigh limit in spectroscopy. We employ an optical quantum memory with spin-wave storage and an embedded processing capability to implement a time-inversion interferometer for input light, projecting the optical field in the symmetric-antisymmetric mode basis. Our tailored measurement achieves a resolution of 15 kHz and requires 20 times less photons than a corresponding Rayleigh-limited conventional method. We demonstrate the advantage of our technique over both conventional spectroscopy and heterodyne measurements, showing potential for application in distinguishing ultra-narrowband emitters, optical communication channels, or signals transduced from lower-frequency domains.
10 citations
TL;DR: In this paper , a high-level architecture of a generic quantum information network (QIN) is presented, with the aim of identifying the main design drivers and critical elements, as well as issues related to standardisation.
Abstract: Abstract Quantum Information Networks (QINs) attract increasing interest, as they enable connecting quantum devices over long distances, thus greatly enhancing their intrinsic computing, sensing, and security capabilities. The core mechanism of a QIN is quantum state teleportation, consuming quantum entanglement, which can be seen in this context as a new kind of network resource. Here we identify use cases per activity sector, including key performance targets, as a reference for the network requirements. We then define a high-level architecture of a generic QIN, before focusing on the architecture of the Space segment, with the aim of identifying the main design drivers and critical elements. A survey of the state-of-the-art of these critical elements is presented, as are issues related to standardisation. Finally, we explain our roadmap to developing the first QINs and detail the already concluded first step, the design and numerical simulation of a Space-to-ground entanglement distribution demonstrator.
6 citations
TL;DR: In this article, a mechanism of strong enhancement of the band Land\'e parameter due to in-plane confinement of holes and the valence-band warping was proposed, which results in uniform magnetic field induced optical anisotropy for the entire quantum dot ensemble.
Abstract: The authors report on a mechanism of strong enhancement of the band Land\'e parameter $q$ due to in-plane confinement of holes and the valence-band warping. This explains the surprisingly large in-plane hole $g$ factor in symmetric self-assembled (In,Ga)As/GaAs quantum dots with $D2d$ symmetry as revealed by coherent optical spectroscopy. The proposed mechanism results in uniform magnetic field induced optical anisotropy for the entire quantum dot ensemble, which is a prerequisite for the realization of spin quantum memories and spin-photon entanglement in the ensemble.
5 citations
TL;DR: In this article , the authors report the deterministic creation of entanglement between an atomic ensemble and a single photon by harnessing the Rydberg blockade, using a process of cyclical retrieving and patching.
Abstract: Hybrid matter-photon entanglement is the building block for quantum networks. It is very favorable if the entanglement can be prepared with a high probability. In this Letter, we report the deterministic creation of entanglement between an atomic ensemble and a single photon by harnessing the Rydberg blockade. We design a scheme that creates entanglement between a single photon's temporal modes and the Rydberg levels that host a collective excitation, using a process of cyclical retrieving and patching. The hybrid entanglement is tested via retrieving the atomic excitation as a second photon and performing correlation measurements, which suggest an entanglement fidelity of 87.8%. Our source of matter-photon entanglement will enable the entangling of remote quantum memories with much higher efficiency.
4 citations
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TL;DR: In this paper, a theorem of Bell, proving that certain predictions of quantum mechanics are inconsistent with the entire family of local hidden-variable theories, is generalized so as to apply to realizable experiments.
Abstract: A theorem of Bell, proving that certain predictions of quantum mechanics are inconsistent with the entire family of local hidden-variable theories, is generalized so as to apply to realizable experiments. A proposed extension of the experiment of Kocher and Commins, on the polarization correlation of a pair of optical photons, will provide a decisive test between quantum mechanics and local hidden-variable theories.
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TL;DR: This work presents a scheme of a quantum repeater that connects a string of (imperfect) entangled pairs of particles by using a novel nested purification protocol, thereby creating a single distant pair of high fidelity.
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