Deterministic spin-photon entanglement from a trapped ion in a fiber Fabry–Perot cavity

AbstractThe development of efficient network nodes is a key element for the realization of quantum networks which promise great capabilities as distributed quantum computing or provable secure communication. We report the realization of a quantum network node using a trapped ion inside a fiber-based Fabry–Perot cavity. We show the generation of deterministic entanglement at a high fidelity of 90.1(17)% between a trapped Yb ion and a photon emitted into the resonator mode. We achieve a success probability for generation and detection of entanglement for a single shot of 2.5 × 10−3 resulting in 62 Hz entanglement rate.

Download Full-text

Policies for elementary links in a quantum network

Quantum ◽

10.22331/q-2021-09-07-537 ◽

2021 ◽

Vol 5 ◽

pp. 537

Author(s):

Sumeet Khatri

Keyword(s):

Decision Process ◽

Success Probability ◽

Coherence Time ◽

Decision Processes ◽

Quantum Network ◽

Quantum Networks ◽

Fundamental Limitations ◽

Process Framework ◽

Entanglement Distribution ◽

Near Term

Distributing entanglement over long distances is one of the central tasks in quantum networks. An important problem, especially for near-term quantum networks, is to develop optimal entanglement distribution protocols that take into account the limitations of current and near-term hardware, such as quantum memories with limited coherence time. We address this problem by initiating the study of quantum network protocols for entanglement distribution using the theory of decision processes, such that optimal protocols (referred to as policies in the context of decision processes) can be found using dynamic programming or reinforcement learning algorithms. As a first step, in this work we focus exclusively on the elementary link level. We start by defining a quantum decision process for elementary links, along with figures of merit for evaluating policies. We then provide two algorithms for determining policies, one of which we prove to be optimal (with respect to fidelity and success probability) among all policies. Then we show that the previously-studied memory-cutoff protocol can be phrased as a policy within our decision process framework, allowing us to obtain several new fundamental results about it. The conceptual developments and results of this work pave the way for the systematic study of the fundamental limitations of near-term quantum networks, and the requirements for physically realizing them.

Download Full-text

Nanophotonic rare-earth quantum memory with optically controlled retrieval

Science ◽

10.1126/science.aan5959 ◽

2017 ◽

Vol 357 (6358) ◽

pp. 1392-1395 ◽

Cited By ~ 79

Author(s):

Tian Zhong ◽

Jonathan M. Kindem ◽

John G. Bartholomew ◽

Jake Rochman ◽

Ioana Craiciu ◽

...

Keyword(s):

Frequency Comb ◽

Essential Elements ◽

Quantum Memory ◽

High Fidelity ◽

Long Distance ◽

Quantum Networks ◽

Network Nodes ◽

Readout Time ◽

On Chip ◽

Photon Source

Optical quantum memories are essential elements in quantum networks for long-distance distribution of quantum entanglement. Scalable development of quantum network nodes requires on-chip qubit storage functionality with control of the readout time. We demonstrate a high-fidelity nanophotonic quantum memory based on a mesoscopic neodymium ensemble coupled to a photonic crystal cavity. The nanocavity enables >95% spin polarization for efficient initialization of the atomic frequency comb memory and time bin–selective readout through an enhanced optical Stark shift of the comb frequencies. Our solid-state memory is integrable with other chip-scale photon source and detector devices for multiplexed quantum and classical information processing at the network nodes.

Download Full-text

Single-Shot Secure Quantum Network Coding for General Multiple Unicast Network with Free One-Way Public Communication

IEEE Transactions on Information Theory ◽

10.1109/tit.2021.3078812 ◽

2021 ◽

pp. 1-1

Author(s):

Go Kato ◽

Masaki Owari ◽

Masahito Hayashi

Keyword(s):

Network Coding ◽

Public Communication ◽

Single Shot ◽

Quantum Network ◽

Quantum Network Coding

Download Full-text

A phononic interface between a superconducting quantum processor and quantum networked spin memories

npj Quantum Information ◽

10.1038/s41534-021-00457-4 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Tomáš Neuman ◽

Matt Eichenfield ◽

Matthew E. Trusheim ◽

Lisa Hackett ◽

Prineha Narang ◽

...

Keyword(s):

Quantum State ◽

Piezoelectric Transducers ◽

High Fidelity ◽

Hybrid Architecture ◽

Quantum Networks ◽

Superconducting Circuit ◽

Artificial Atom ◽

Experimental Parameters ◽

Quantum Processor ◽

State Spin

AbstractWe introduce a method for high-fidelity quantum state transduction between a superconducting microwave qubit and the ground state spin system of a solid-state artificial atom, mediated via an acoustic bus connected by piezoelectric transducers. Applied to present-day experimental parameters for superconducting circuit qubits and diamond silicon-vacancy centers in an optimized phononic cavity, we estimate quantum state transduction with fidelity exceeding 99% at a MHz-scale bandwidth. By combining the complementary strengths of superconducting circuit quantum computing and artificial atoms, the hybrid architecture provides high-fidelity qubit gates with long-lived quantum memory, high-fidelity measurement, large qubit number, reconfigurable qubit connectivity, and high-fidelity state and gate teleportation through optical quantum networks.

Download Full-text

Routing Strategies for High-Fidelity, Multiplexed Quantum Networks

10.1364/cleo_qels.2021.fth2n.6 ◽

2021 ◽

Author(s):

Yuan Lee ◽

Eric Bersin ◽

Wenhan Dai ◽

Dirk Englund

Keyword(s):

High Fidelity ◽

Quantum Networks

Download Full-text

High-Fidelity Preservation of Quantum Information During Trapped-Ion Transport

Physical Review Letters ◽

10.1103/physrevlett.120.010501 ◽

2018 ◽

Vol 120 (1) ◽

Cited By ~ 12

Author(s):

Peter Kaufmann ◽

Timm F. Gloger ◽

Delia Kaufmann ◽

Michael Johanning ◽

Christof Wunderlich

Keyword(s):

Quantum Information ◽

Ion Transport ◽

High Fidelity ◽

Trapped Ion

Download Full-text

Implementation of a 46-node quantum metropolitan area network

npj Quantum Information ◽

10.1038/s41534-021-00474-3 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Teng-Yun Chen ◽

Xiao Jiang ◽

Shi-Biao Tang ◽

Lei Zhou ◽

Xiao Yuan ◽

...

Keyword(s):

Metropolitan Area ◽

Key Management ◽

Text Messaging ◽

Secure Communication ◽

Field Tests ◽

Area Network ◽

Quantum Network ◽

Standard Equipment ◽

Metropolitan Area Network ◽

Network Maintenance

AbstractQuantum key distribution (QKD) enables secure key exchanges between two remote users. The ultimate goal of secure communication is to establish a global quantum network. The existing field tests suggest that quantum networks are feasible. To achieve a practical quantum network, we need to overcome several challenges including realizing versatile topologies for large scales, simple network maintenance, extendable configuration and robustness to node failures. To this end, we present a field operation of a quantum metropolitan-area network with 46 nodes and show that all these challenges can be overcome with cutting-edge quantum technologies. In particular, we realize different topological structures and continuously run the network for 31 months, by employing standard equipment for network maintenance with an extendable configuration. We realize QKD pairing and key management with a sophisticated key control centre. In this implementation, the final keys have been used for secure communication such as real-time voice telephone, text messaging and file transmission with one-time pad encryption, which can support 11 pairs of users to make audio calls simultaneously. Combined with intercity quantum backbone and ground–satellite links, our metropolitan implementation paves the way toward a global quantum network.

Download Full-text