Remote Quantum Research Articles

Hierarchical Controlled Joint Remote Implementation of the Partially Unknown Operations of m Qudits via m High-Dimensional Entangled States.

We present a protocol for the hierarchical controlled joint remote implementation of the partially unknown operations of m qudits belonging to some restricted sets by using m multiparticle high-dimensional entangled states as the quantum channel. All the senders share the information of the partially unknown operations and cooperate with each other to implement the partially unknown operations on the remote receiver's quantum system. The receivers are hierarchized in accordance with their abilities to reconstruct the desired state. The agents in the upper grade need only cooperate with one of the lower-grade agents, and the agents in the lower grade need the cooperation of all the other agents. The protocol has the advantage of having high channel capacity by using a high-dimensional entangle state as the quantum channel for the hierarchial controlled joint remote implementation of partially unknown quantum operations of m qudits.

Automatic architecture design for distributed quantum computing

Abstract In distributed quantum computing (DQC), quantum hardware design mainly focuses on providing as many as possible high-quality inter-chip connections. Meanwhile, quantum software tries its best to reduce the required number of remote quantum gates between chips. However, this “hardware first, software follows” methodology may not fully exploit the potential of DQC. Inspired by classical software–hardware co-design, this paper explores the design space of application-specific DQC architectures. More specifically, we propose AutoArch, an automated quantum chip network (QCN) structure design tool. With qubits grouping followed by a customized QCN design, AutoArch can generate a near-optimal DQC architecture suitable for target quantum algorithms. Experimental results show that the DQC architecture generated by AutoArch can outperform other general QCN architectures when executing target quantum algorithms.

Hardware requirements for trapped-ion-based verifiable blind quantum computing with a measurement-only client

Abstract In blind quantum computing (BQC), a user with a simple client device can perform a quantum computation on a remote quantum server such that the server cannot gain knowledge about the computation. Here, we numerically investigate hardware requirements for verifiable BQC using an ion trap as server and a distant measurement-only client. While the client has no direct access to quantum-computing resources, it can remotely execute quantum programs on the server by measuring photons emitted by the trapped ion. We introduce a numerical model for trapped-ion quantum devices in NetSquid, a discrete-event simulator for quantum networks. Using this, we determine the minimal hardware requirements on a per-parameter basis to perform the verifiable BQC protocol. We benchmark these for a five-qubit linear graph state, with which any single-qubit rotation can be performed, where client and server are separated by 50 km. Current state-of-the-art ion traps satisfy the minimal requirements on a per-parameter basis, but all current imperfections combined make it impossible to perform the blind computation securely over 50 km using existing technology. Using a genetic algorithm, we determine the set of hardware parameters that minimises the total improvements required, finding directions along which to improve hardware to reach our threshold error probability that would enable experimental demonstration. In this way, we lay a path for the near-term experimental progress required to realise the implementation of verifiable BQC over a 50 km distance.

Remote and controlled quantum teleportation network of the polarization squeezed state

Quantum teleportation is a building block in quantum computation and quantum communication. The continuous-variable polarization squeezed state is a key resource in quantum networks, offering advantages for long-distance distribution and direct interfacing of quantum nodes. Although polarization squeezed state has been generated and distributed between remote users, it is a long-standing goal to implement controlled quantum teleportation of the polarization squeezed state with multiple remote users. Here, we propose a feasible scheme to teleport a polarization squeezed state among multiple remote users under control. The polarization state is transferred between different remote quantum networks, and the controlled quantum teleportation of the polarization state can be implemented in one quantum network involving multiple remote users. The results show that such a controlled quantum teleportation can be realized with 36 users through about 6-km free-space or fiber quantum channels, where the fidelity of 0.352 is achieved beyond the classical limit of 0.349 with an input squeezing variance of 0.25. This scheme provides a direct reference for the experimental implementation of remote and controlled quantum teleportation of polarization states, thus enabling more teleportation-based quantum network protocols.

Design, Development, and Formative Evaluation of a Hybrid Remote Quantum Laboratory Supporting HBCU Partnerships

Quantum information science and engineering are expanding and scaling worldwide. As government and industry push to expand quantum applications around the world, education institutions scramble to train the next generation of quantum-aware engineers in the Quantum pipeline. However, as educational institutions seek to expand the pipeline, not all learners have access to Quantum training or equipment. Quantum laboratories, an expensive component of STEM education, often remain exclusively accessible to institutions with affluence and funding, thus creating systemic barriers for underrepresented learners to the Quantum pipeline. This design-based case study describes the three-year design and development of a hybrid remote online Quantum laboratory in partnership with historically black colleges and universities across the US with the goal of expanding access for underrepresented learners to Quantum training. The study describes the prototypical design, development, and formative evaluation of the prototype’s iterations and reflects on design decisions made resulting from formative feedback during the design process.

Quantum teleportation in Heisenberg chain with magnetic-field gradient under intrinsic decoherence

One of the most appealing quantum communication protocols is quantum teleportation, which involves sharing entanglement between the sender and receiver of the quantum state. We address the two-qubit quantum teleportation based on the Heisenberg XYZ chain with a magnetic-field gradient affected by intrinsic decoherence. An atomic spin chain is primarily coupled to the linear gradient of the magnetic field in the x-direction, with the assumption that the magnetic field varies linearly with the position of the atom. By using the concepts of fidelity and average fidelity in the presence of the magnetic field gradient and under the effect of intrinsic decoherence in the current model, and considering the variables of the system, an improved quantum teleportation can be achieved. In addition, using the concept of remote quantum estimation, we examine remote quantum sensing in this article, which is very useful in quantum communication.

Optical clocks at sea

Deployed optical clocks will improve positioning for navigational autonomy1, provide remote time standards for geophysical monitoring2 and distributed coherent sensing3, allow time synchronization of remote quantum networks4,5 and provide operational redundancy for national time standards. Although laboratory optical clocks now reach fractional inaccuracies below 10−18 (refs. 6,7), transportable versions of these high-performing clocks8,9 have limited utility because of their size, environmental sensitivity and cost10. Here we report the development of optical clocks with the requisite combination of size, performance and environmental insensitivity for operation on mobile platforms. The 35 l clock combines a molecular iodine spectrometer, fibre frequency comb and control electronics. Three of these clocks operated continuously aboard a naval ship in the Pacific Ocean for 20 days while accruing timing errors below 300 ps per day. The clocks have comparable performance to active hydrogen masers in one-tenth the volume. Operating high-performance clocks at sea has been historically challenging and continues to be critical for navigation. This demonstration marks a significant technological advancement that heralds the arrival of future optical timekeeping networks.

Factoring 15 with a remote quantum computer: a complete guide for beginners

We present, for the non-specialist, an experimental implementation of Shor’s factoring algorithm. We are unaware of any other single reference that explains, in a beginner-friendly way, complete circuits that implement Shor’s algorithm. We perform the experiment with IBM quantum processors, which are remotely accessible online for free. We reproducibly factor 15 with one 7-qubit processor (ibm_perth), while four other quantum processors exhibit excessive error.

High-fidelity entanglement routing in quantum networks

Quantum networks, endowed with their distinct quantum properties, are poised to emerge as indispensable platforms for the implementation of quantum information technology applications in the near future. Within the realm of quantum networks, the transmission of remote quantum information presents a pivotal and intricate challenge, commonly referred to as the entanglement routing problem. While previous efforts have delved into the intricacies of entanglement routing, there has been a notable oversight concerning the crucial parameter of entanglement fidelity. Hence, this paper introduces a novel Purification-enabled Entanglement Routing Algorithm (PERA). Initially, PERA utilizes the network throughput as the routing metric and ensures fidelity guarantees on all nodes in the link through a hop-by-hop purification process. Subsequently, acknowledging the probabilistic nature of entanglement purification, a strategy involving multiple attempts at purification is employed. Finally, a comprehensive utility function is deployed to address the path selection problem for multiple source–destination pairs. Numerical simulations confirm that PERA establishes entanglement connections with outstanding fidelity guarantees. Concurrently, PERA outperforms the baseline algorithm in terms of network throughput and resource utilization.

Experimental Generation of Spin-Photon Entanglement in Silicon Carbide.

A solid-state approach for quantum networks is advantageous, as it allows the integration of nanophotonics to enhance the photon emission and the utilization of weakly coupled nuclear spins for long-lived storage. Silicon carbide, specifically point defects within it, shows great promise in this regard due to the easy of availability and well-established nanofabrication techniques. Despite of remarkable progresses made, achieving spin-photon entanglement remains a crucial aspect to be realized. In this Letter, we experimentally generate entanglement between a silicon vacancy defect in silicon carbide and a scattered single photon in the zero-phonon line. The spin state is measured by detecting photons scattered in the phonon sideband. The photonic qubit is encoded in the time-bin degree of freedom and measured using an unbalanced Mach-Zehnder interferometer. Photonic correlations not only reveal the quality of the entanglement but also verify the deterministic nature of the entanglement creation process. By harnessing two pairs of such spin-photon entanglement, it becomes straightforward to entangle remote quantum nodes at long distance.

Near-field coupling of interlayer excitons in MoSe2/WSe2 heterobilayers to surface plasmon polaritons.

Two-dimensional (2D) transition metal dichalcogenides have emerged as promising quantum functional blocks benefitting from their unique combination of spin, valley, and layer degrees of freedom, particularly for the tremendous flexibility of moiré superlattices formed by van der Waals stacking. These degrees of freedom coupled with the enhanced Coulomb interaction in 2D structures allow excitons to serve as on-chip information carriers. However, excitons are spatially circumscribed due to their low mobility and limited lifetime. One way to overcome these limitations is through the coupling of excitons with surface plasmon polaritons (SPPs), which facilitates an interaction between remote quantum states. Here, we showcase the successful coupling of SPPs with interlayer excitons in molybdenum diselenide/tungsten diselenide heterobilayers. Our results indicate that the valley polarization can be efficiently transferred to SPPs, enabling preservation of polarization information even after propagating tens of micrometers.

Entanglement Routing Design Over Quantum Networks

Quantum networks have emerged as a future platform for quantum information exchange and applications, with promising capabilities far beyond traditional communication networks. Remote quantum entanglement is an essential component of a quantum network. How to efficiently design a multi-routing entanglement protocol is a fundamental yet challenging problem. In this paper, we study a quantum entanglement routing problem to simultaneously maximize the number of quantum-user pairs and their expected throughput. Our approach is to formulate the problem as two sequential integer programming problems. We propose efficient entanglement routing algorithms for these two optimization problems and analyze their time complexity and performance bounds. Evaluation results highlight that our approach outperforms existing solutions in both the number of quantum-user pairs served and network throughput.

Controlled Cyclic and Bidirectional Hybrid Quantum Communication of Arbitrary Two‐Qubit States

AbstractHybrid quantum communication with the combination of quantum teleportation and remote preparation is hopeful for promoting the development of quantum networks and enriching the diversity of quantum network communication. To improve the communication efficiency and enhance the scalability of the quantum networks, a meaningful protocol for controlled cyclic and bidirectional hybrid quantum communication of arbitrary two‐qubit states is proposed, which allows quantum information to be transmitted simultaneously in both directions among multiple participants. With the permission of one controller, each observer can simultaneously transmit arbitrary known two‐qubit states and unknown ones to their adjacent observers, by implementing remote preparation and quantum teleportation in the clockwise and counterclockwise directions. Furthermore, the participants just carry out some quantum measurements and recovery operations to achieve the communication target, and the desired states can be attained with a unit success probability, thus the protocol is deterministic. Finally, some comparisons are also made with other similar protocols, which shows that the protocol is better in qubit efficiency and communication capacity.

Design of remote data quantum system for geological oil extraction based on ARM and GPRS

Design of remote data quantum system for geological oil extraction based on ARM and GPRS

Multi-client distributed blind quantum computation with the Qline architecture

Universal blind quantum computing allows users with minimal quantum resources to delegate a quantum computation to a remote quantum server, while keeping intrinsically hidden input, algorithm, and outcome. State-of-art experimental demonstrations of such a protocol have only involved one client. However, an increasing number of multi-party algorithms, e.g. federated machine learning, require the collaboration of multiple clients to carry out a given joint computation. In this work, we propose and experimentally demonstrate a lightweight multi-client blind quantum computation protocol based on a recently proposed linear quantum network configuration (Qline). Our protocol originality resides in three main strengths: scalability, since we eliminate the need for each client to have its own trusted source or measurement device, low-loss, by optimizing the orchestration of classical communication between each client and server through fast classical electronic control, and compatibility with distributed architectures while remaining intact even against correlated attacks of server nodes and malicious clients.

Hierarchical Controlled Hybrid Quantum Communication Based on Six-Qubit Entangled States in IoT.

The rapid development and extensive application of the Internet of Things (IoT) have brought new challenges and opportunities to the field of communication. By integrating quantum secure communication with the IoT, we can provide a higher level of security and privacy protection to counteract security threats in the IoT. In this paper, a hybrid quantum communication scheme using six-qubit entangled states as a channel is proposed for specific IoT application scenarios. This scheme achieves hierarchical control of communication protocols on a single quantum channel. In the proposed scheme, device A transmits data to device B through quantum teleportation, while device B issues control commands to device A through remote quantum state preparation technology. These two tasks are controlled by control nodes C and D, respectively. The transmission of information from device A to device B is a relatively less important task, which can be solely controlled by control node C. On the other hand, issuing control commands from device B to device A is a more crucial task requiring joint control from control nodes C and D. This paper describes the proposed scheme and conducts simulation experiments using IBM's Qiskit Aer quantum computing simulator. The results demonstrate that the fidelity of the quantum teleportation protocol (QTP) and the remote state preparation protocol (RSP) reach an impressive value of 0.999, fully validating the scheme's feasibility. Furthermore, the factors affecting the fidelity of the hybrid communication protocol in an IoT environment with specific quantum noise are analyzed. By combining the security of quantum communication with the application scenarios of the IoT, this paper presents a new possibility for IoT communication.

Heralded quantum multiplexing entanglement between stationary qubits via distribution of high-dimensional optical entanglement.

Quantum entanglement between pairs of remote quantum memories (QMs) is a prerequisite for realizing many applications in quantum networks. Here, we present a heralded protocol for the parallel creation of quantum entanglement among multiple pairs of QMs placed in spatially separated nodes, where each QM, encoding a stationary qubit, couples to an optical cavity and deterministically interacts with single photons. Our protocol utilizes an entangled photon pair encoded in the high-dimensional time-bin degree of freedom to simultaneously entangle multiple QM pairs, and is efficient in terms of reducing the time consumption and photon loss during transmission. Furthermore, our approach can be extended to simultaneously support spatial-temporal multiplexing, as its success is heralded by the detection of single photons. These distinguishing features make our protocol particularly useful for long-distance quantum communication and large-scale quantum networks.

A Scheme for Quantum Teleportation and Remote Quantum State Preparation of IoT Multiple Devices.

With the continuous development of the Internet of Things (IoT) technology, the industry's awareness of the security of the IoT is also increasing, and the adoption of quantum communication technology can significantly improve the communication security of various devices in the IoT. This paper proposes a scheme of controlled remote quantum state preparation and quantum teleportation based on multiple communication parties, and a nine-qubit entanglement channel is used to achieve secure communication of multiple devices in the IoT. The channel preparation, measurement operation, and unitary operation of the scheme were successfully simulated on the IBM Quantum platform, and the entanglement degree and reliability of the channel were verified through 8192 shots. The scheme's application in the IoT was analyzed, and the steps and examples of the scheme in the secure communication of multiple devices in the IoT are discussed. By simulating two different attack modes, the effect of the attack on the communication scheme in the IoT was deduced, and the scheme's high security and anti-interference ability was analyzed. Compared with other schemes from the two aspects of principle and transmission efficiency, it is highlighted that the advantages of the proposed scheme are that it overcomes the single fixed one-way or two-way transmission protocol form of quantum teleportation in the past and can realize quantum communication with multiple devices, ensuring both security and transmission efficiency.

Multichip multidimensional quantum networks with entanglement retrievability.

Quantum networks provide the framework for quantum communication, clock synchronization, distributed quantum computing, and sensing. Implementing large-scale and practical quantum networks relies on the development of scalable architecture and integrated hardware that can coherently interconnect many remote quantum nodes by sharing multidimensional entanglement through complex-medium quantum channels. We demonstrate a multichip multidimensional quantum entanglement network based on mass-manufacturable integrated-nanophotonic quantum node chips fabricated on a silicon wafer by means of complementary metal-oxide-semiconductor processes. Using hybrid multiplexing, we show that multiple multidimensional entangled states can be distributed across multiple chips connected by few-mode fibers. We developed a technique that can efficiently retrieve multidimensional entanglement in complex-medium quantum channels, which is important for practical uses. Our work demonstrates the enabling capabilities of realizing large-scale practical chip-based quantum entanglement networks.

A Remote Quantum Error-Correcting Code Preparation Protocol on Cluster States

The blind quantum computation (BQC) protocol allows for privacy-preserving remote quantum computations. In this paper, we introduce a remote quantum error correction code preparation protocol for BQC using a cluster state and analyze its blindness in the measurement-based quantum computation model. Our protocol requires fewer quantum resources than previous methods, as it only needs weak coherent pulses, eliminating the need for quantum memory and limited quantum computing. The results of our theoretical analysis and simulations show that our protocol requires fewer quantum resources compared to non-coding methods with the same qubit error rate.