Transmission Of Quantum States Research Articles

Transmitting squeezed states in a cascaded cavity-magnonic system

The squeezed state has wide applications in quantum information and metrology. This work demonstrates the long-distance transmission of a squeezed state, where we utilize a cavity-magnonic system composed of a cascaded cavity and a yttrium iron garnet sphere. The squeezed source, originating from a flux-driven Josephson parametric amplifier, is mediated through six cavity modes and ultimately transmitted to magnon mode. With appropriate detuning matching, state transmission can be blocked at any mode, and the difference in squeezing phase between adjacent modes is π. Squeezed magnons exhibit high robustness against environmental temperature and magnetic damping. Our work provides prior guidance for multi-mode transmission of quantum states in continuous variable systems.

Performance optimization of continuous-variable quantum teleportation with generalized photon-varying non-Gaussian operations

Continuous variable quantum teleportation provides a path to the long-distance transmission of quantum states. Photon-varying non-Gaussian operations have been shown to improve the fidelity of quantum teleportation when integrated into the protocol. However, for a given type of non-Gaussian operation, the achievable fidelity varies with the parameters associated with the operation. Previous work only focused on particular settings of the parameters, over which an optimization was missing. The potential of such operations is not fully uncovered. Given a fixed non-Gaussian operation, the achievable fidelity also varies with input states. An operation that increases the fidelity for teleporting one class of states might do the contrary for other classes of states. A performance metric, upon which an operation is optimized, suitable for different input states, is also missing. In this work, we build a framework for photon-varying non-Gaussian operations for multimode states, upon which we propose a performance metric suitable for arbitrary teleportation input states. We then apply the new metric to evaluate different types of non-Gaussian operations. Starting from simple multiphoton photon subtraction and photon addition, we find that increasing the number of ancillary photons involved in the operation does not guarantee performance improvement. We then investigate a generalization of the operations mentioned above, finding that operations that approximate a particular form provide the best improvement. The results provided here will be valuable for real-world implementations of quantum teleportation networks and applications that harness the non-Gaussianity of quantum states. Published by the American Physical Society 2024

Measurement‐Device‐Independent Quantum Secret Sharing

AbstractQuantum secret sharing has many important applications in quantum communication and secure multiparty computing. In this work, a novel measurement‐device‐independent protocol for three‐party quantum secret sharing is put forward, in which the dealer and two sharers are required to prepare Greenberger‐Horne‐Zeilinger states and single particles, respectively, but they only need to perform single‐particle measurement. As a result, this protocol is feasible in experiments by using current technologies. More importantly, it can extend the spatial distance among three participants for quantum state transmissions at least 15.47% compared to the previous protocols.

Large teleportation of two-qubit state between non-neighboring nodes based on the utilization of multiple cluster states within quantum networks

The transmission of quantum states over extended distances is constrained by photon losses, ruling out direct amplification akin to classical telecommunications due to the non-cloning theorem. Overcoming this challenge involves implementing quantum repeater protocols that leverage entanglement swapping to create long-distance entanglement from shorter distances. A novel multi-hop quantum teleportation scheme, blending concepts from quantum repeaters and teleportation, is under exploration. It aims to transfer arbitrary two-qubit states between two distant parties, even in the absence of a direct quantum channel. Intermediate nodes, connected via a four-qubit entangled cluster state as quantum channels, are introduced based on a more general routing protocol. Bell measurements are independently conducted by the source node (Alice) and all intermediate nodes, with simultaneous transmission of measurement results, significantly reducing time consumption. Determining the quantum state from Bell measurement results requires only the destination node (Bob) for a simple unitary transformation. Moreover, this protocol holds promise for implementation on the IBM Quantum Experience platform once the requisite quantum circuits are designed. This overview encompasses both the theoretical and simulated status of the proposed scheme, with simulated findings incorporated into quantum state tomography to verify the accuracy of the transmitted quantum state.

Topological protection of dual-polarization biphoton states in photonic crystals

Polarization control is a major issue in topological quantum optics that limits reliable generation and transmission of quantum states. This study presents what we believe to be a novel topological photonic crystal design that provides topological protection for biphoton pairs for both TE and TM polarization. By well-designed cell configurations within the lattice, two topological boundaries emerge that can accommodate TM and TE modes at the same time. By adjusting the dispersion curves, we can further design nonlinear four-wave mixing processes within the topological photonic crystals and provide theoretical explanations for the entanglement of the dual-polarization biphoton states. Numerical results confirm the robust transport of entangled photon pairs, even when subjected to sharp bending. Moreover, combining the dual-polarization topological photonic crystal with a polarization beam splitter enables the preparation of polarization-encoded maximally entangled states. Our work exhibits significant potential for applications in robust optical quantum information processing and quantum secure communication.

Faithful quantum teleportation through common and independent qubit-noise configurations and multi-parameter estimation in the output of teleported state

Quantum teleportation allows the transmission of unknown quantum states over arbitrary distances. This paper studies quantum teleportation via two non-interacting qubits coupled to local fields and Ornstein Uhlenbeck noise. We consider two different qubit-noise configurations, i.e., common qubit-noise interactions and independent qubit-noise interactions. We introduce a Gaussian Ornstein Uhlenbeck process to take into account the noisy effects of the local external fields. Furthermore, we address the intrinsic behavior of classical fields toward single- and two-qubit quantum teleportation as a function of various parameters. Additionally, using a quantum estimation theory, we study single- and multi-parameter estimation of the teleported state output for single and two-qubit quantum teleportation scenarios. One important application of this work is obtaining more valuable information in quantum remote sensing.

Long-distance transmission of arbitrary quantum states between spatially separated microwave cavities.

Long-distance transmission between spatially separated microwave cavities is a crucial area of quantum information science and technology. In this work, we present a method for achieving long-distance transmission of arbitrary quantum states between two microwave cavities, by using a hybrid system that comprises two microwave cavities, two nitrogen-vacancy center ensembles (NV ensembles), two optical cavities, and an optical fiber. Each NV ensemble serves as a quantum transducer, dispersively coupling with a microwave cavity and an optical cavity, which enables the conversion of quantum states between a microwave cavity and an optical cavity. The optical fiber acts as a connector between the two optical cavities. Numerical simulations demonstrate that our method allows for the transfer of an arbitrary photonic qubit state between two spatially separated microwave cavities with high fidelity. Furthermore, the method exhibits robustness against environmental decay, parameter fluctuations, and additive white Gaussian noise. Our approach offers a promising way for achieving long-distance transmission of quantum states between two spatially separated microwave cavities, which may have practical applications in networked large-scale quantum information processing and quantum communication.

Modulation of topological phase transition and topological quantum state of magnon-photon in one-dimensional coupled cavity lattices

We propose a theoretical scheme to study the topological properties of magnon-photon in a one-dimensional coupled cavity lattice. Each unit cell is composed of the cavity microwave photon and the magnon, where the magnon is placed inside the cavity. The coupling of cavity microwave photon and magnon is controlled by an external magnetic field, and multiple cavities are coupled with each other to form a one-dimensional coupled cavity lattice system. Here, we study the topological phase transition and topological quantum channels of magnon-photon in the system by adjusting the magnon-photon coupling. Firstly, considering odd and even number lattices, we analyze and discuss the energy spectrum and the edge state in one-dimensional coupled cavity lattices. It is found that the energy band of the system is symmetric, and the edge states in the energy gap have time reversal symmetry, which makes the system topologically protected. At the same time, it is also noted that the maximum value, flipping, and period of the energy spectrum have changed, and the region of the edge state has expanded and extended. In addition, the edge state distribution can undergo the flipping process, which can achieve multi-channel topological quantum state transmission. Besides, considering the presence of defects and disorder in the system, it is found that when the random defect potential is small, the edge state of the system is robust to it, but when the random defect potential is large, the fluctuation of the energy band will be enhanced, and the edge state will be submerged in the energy band. However, when the disorder is very small, it can cause band fluctuations and flipping phenomena, and the edge state is robust to it, indicating the topological protection of the edge state. This work offers an effective way to study topological magnon-photon, which will have promising applications in quantum information processing.

Effects of non-Markovian squeezed bath on the dynamics of open systems

Control of the dynamics of an open quantum system is crucial in quantum information processing. Basically there are two ways: one is the control on the system and the other is tuning the bath parameters. In this paper, we use the latter to analyze the non-Markovian dynamics of the open system. The model is that the system is immersed in non-Markovian squeezed baths. For the dynamics, a non-Markovian master equation is obtained using the quantum state diffusion (QSD) equation technique for the weak system–bath couplings. We take the adiabatic evolution or quantum state transmission as examples to analyze the effects of the bath parameters: non-Markovianity γ, the squeezed direction θ and squeezed strength r. For the adiabatic or state transmission fidelity, the calculation results show that they both can be enhanced by a smaller γ or bigger p-quadrature. Interestingly, when 0<θ<π/2, the squeezed quadrature is determined by the combination of r and θ, and by numerical simulation we find that the fidelity peak occurs at r=1−2θ/π. The fidelities increase with increasing r when r∈(0,1−2θ/π]. When θ≥π/2, lower fidelities are obtained due to the squeezed baths. Our results show that the dynamics of the open systems can be effectively controlled by reservoir engineering.

Controlled cyclic remote preparation

Multi-party quantum communication has gradually attracted widespread attention. To realize the perfect transmission of quantum states among multiple participants, a novel multi-party controlled cyclic remote preparation protocol for arbitrary single-qubit states with three senders is proposed. With the permission of one controller, each sender can transmit an arbitrary single-qubit state to its neighbor. In addition, we give a universal protocol for multi-party controlled cyclic remote preparation of arbitrary single-qubit states in the case of multiple senders, which can realize deterministic cyclic preparation of multiple quantum states in one direction. The scheme shows that the communication task can be successfully achieved only if all senders cooperate with the controller, and there is no need for the senders to employ information splitting and additional operations before performing measurements. Finally, we discuss the cyclic remote preparation protocol with three senders under five types of noisy environment, and the closeness between the output state and original state is measured by calculating fidelity.

SimQN: A Network-Layer Simulator for the Quantum Network Investigation

Along with the rapid development of quantum information technologies, quantum networks that transmit quantum states have gradually shifted from laboratory to reality. However, the high cost of building a quantum network testbed seriously hinders the research progress of quantum networks, and the existing simulators have been developed with less exposure to network models. To overcome those deficiencies, this article proposes a new discrete-event driven network-layer simulation framework named SimQN, available at https://github.com/ertuil/SimQN, to provide full functionalities of the quantum networking simulation. The design goal of SimQN is to make it easy-to-configure while providing high performance and accurate simulation capability. We present multiple simulation physical backends to enable different functionalities and reduce computational overhead. The modularized SimQN also provides reusable network protocols and utilities to release the large-scale quantum networking evaluation burden. We present several demonstrations and analyses to illustrate the protocol design and the performance of SimQN.

Enhancing quantum teleportation efficacy with noiseless linear amplification.

Quantum teleportation constitutes a fundamental tool for various applications in quantum communication and computation. However, state-of-the-art continuous-variable quantum teleportation is restricted to moderate fidelities and short-distance configurations. This is due to unavoidable experimental imperfections resulting in thermal decoherence during the teleportation process. Here we present a heralded quantum teleporter able to overcome these limitations through noiseless linear amplification. As a result, we report a high fidelity of 92% for teleporting coherent states using a modest level of quantum entanglement. Our teleporter in principle allows nearly complete removal of loss induced onto the input states being transmitted through imperfect quantum channels. We further demonstrate the purification of a displaced thermal state, impossible via conventional deterministic amplification or teleportation approaches. The combination of high-fidelity coherent state teleportation alongside the purification of thermalized input states permits the transmission of quantum states over significantly long distances. These results are of both practical and fundamental significance; overcoming long-standing hurdles en route to highly-efficient continuous-variable quantum teleportation, while also shining new light on applying teleportation to purify quantum systems from thermal noise.

Space-based quantum networking in the presence of a nuclear disturbed environment.

Space-based quantum networks provide a means for near-term long-distance transmission of quantum information. This article analyzed the performance of a downlink quantum network between a low-Earth-orbit satellite and an observatory operating in less-than-ideal atmospheric conditions. The effects from fog, haze, and a nuclear disturbed environment on the long-range distribution of quantum states were investigated. A density matrix that estimates the quantum state by capturing the effects from increased signal loss and elevated background noise to estimate the state fidelity of the transmitted quantum state was developed. It was found that the nuclear disturbed environment and other atmospheric effects have a degrading effect on the quantum state. These environments impede the ability to perform quantum communications for the duration of the effects. In the case of the nuclear disturbed environment, the nuclear effects subside quickly, and network performance should return to normal by the next satellite pass.

Single-Photon-Memory Measurement-Device-Independent Quantum Secure Direct Communication—Part II: A Practical Protocol and its Secrecy Capacity

In Part I of this two-part letter on single-photon-memory measurement-device-independent quantum secure direct communication (SPMQC), we reviewed the fundamentals and evolution of quantum secure direct communication (QSDC). In this Part II, we propose a practical protocol and analyze its secrecy capacity. In order to eliminate the security loopholes resulting from practical detectors, the measurement-device-independent (MDI) QSDC protocol has been proposed. However, block-based transmission of quantum states is utilized in MDI-QSDC, which requires practical quantum memory that is still unavailable at the time of writing. For circumventing this impediment, we propose the SPMQC protocol for dispensing with high-performance quantum memory. The performance of the proposed protocol is characterized by simulations considering realistic experimental parameters, and the results show that it is feasible to implement SPMQC by relying on existing technology.

Quantum communication through devices with indefinite input-output direction

Certain quantum devices, such as half-wave plates and quarter-wave plates in quantum optics, are bidirectional, meaning that the roles of their input and output ports can be exchanged. Bidirectional devices can be used in a forward mode and a backward mode, corresponding to two opposite choices of the input-output direction. They can also be used in a coherent superposition of the forward and backward modes, giving rise to new operations with indefinite input-output direction. In this work we explore the potential of input-output indefiniteness for the transfer of classical and quantum information through noisy channels. We first formulate a model of communication from a sender to a receiver via a noisy channel used in indefinite input-output direction. Then, we show that indefiniteness of the input-output direction yields advantages over standard communication protocols in which the given noisy channel is used in a fixed input-output direction. These advantages range from a general reduction of noise in bidirectional processes, to heralded noiseless transmission of quantum states, and, in some special cases, to a complete noise removal. The noise reduction due to input-output indefiniteness can be experimentally demonstrated with current photonic technologies, providing a way to investigate the operational consequences of exotic scenarios characterised by coherent quantum superpositions of forward-time and backward-time processes.

Asymmetric Circular Controlled Quantum State Transmission Scheme in Ideal and Noisy Environment

Asymmetric Circular Controlled Quantum State Transmission Scheme in Ideal and Noisy Environment

Selectively gas-filled anti-resonant hollow-core fibers for broadband high-purity LP11 mode guidance.

An anti-resonant hollow-core fiber capable of propagating the LP11 mode with high purity and over a wide wavelength range is proposed and demonstrated. The suppression of the fundamental mode relies on the resonant coupling with specific gas selectively filled into the cladding tubes. After a length of 2.7 m, the fabricated fiber shows a mode extinction ratio of over 40 dB at 1550 nm and above 30 dB in a wavelength range of 150 nm. The loss of the LP11 mode is measured to be 2.46 dB/m at 1550 nm. We discuss the potential application of such fibers in high-fidelity high-dimensional quantum state transmission.

Optimally Controlled Non-Adiabatic Quantum State Transmission in the Presence of Quantum Noise

Pulse-controlled non-adiabatic quantum state transmission (QST) was proposed many years ago. However, in practice environmental noise inevitably damages communication quality in the proposal. In this paper, we study the optimally controlled non-adiabatic QST in the presence of quantum noise. By using the Adam algorithm, we find that the optimal pulse sequence can dramatically enhance the transmission fidelity of such an open system. In comparison with the idealized pulse sequence in a closed system, it is interesting to note that the improvement of the fidelity obtained by the Adam algorithm can even be better for a bath strongly coupled to the system. Furthermore, we find that the Adam algorithm remains powerful for different numbers of sites and different types of Lindblad operators, showing its universality in performing optimal control of quantum information processing tasks.

Frequency-Multiplexed Storage and Distribution of Narrowband Telecom Photon Pairs over a 10-km Fiber Link with Long-Term System Stability

The ability to transmit quantum states over long distances is a fundamental requirement of the quantum internet and is reliant upon quantum repeaters. Quantum repeaters involve entangled photon sources that emit and deliver photonic entangled states at high rates and quantum memories that can temporarily store quantum states. Improvement of the entanglement distribution rate is essential for quantum repeaters, and multiplexing is expected to be a breakthrough. However, limited studies exist on multiplexed photon sources and their coupling with a multiplexed quantum memory. Here, we demonstrate the storing of a frequency-multiplexed two-photon source at telecommunication wavelengths in a quantum memory accepting visible wavelengths via wavelength conversion after 10-km distribution. To achieve this, quantum systems are connected via wavelength conversion with a frequency stabilization system and a noise reduction system. The developed system was stably operated for more than 42 h. Therefore, it can be applied to quantum repeater systems comprising various physical systems requiring long-term system stability.

Topological phase transitions and topological quantum states modulated by the counter-rotating wave terms in a one-dimensional superconducting microwave cavity lattice

We propose a one-dimensional lattice theory scheme based on superconducting microwave cavities, which includes two different types of microwave cavity unit cells. The coupling between unit cells is controlled by flux qubits to simulate and study their topological insulator characteristics. Specifically, a one-dimensional superconducting microwave cavity lattice scheme with a p-wave superconducting pairing term is achieved by mapping the counter-rotating wave terms to the p-wave superconducting pairing term. We found that the p-wave superconducting pairing term can modulate the topological quantum state of the system, allowing for the creation of topological quantum information transmission channels with four edge states. In addition, when the p-wave superconducting pairing term and the nearest-neighbor interaction exist, we find that the energy band undergoes fluctuations, inducing the generation of new energy bands, but the degeneracy of the edge states remains stable, which can achieve multiple topological quantum state transmission paths. However, when its regulatory value exceeds the threshold, the energy gap of the system will close, causing the edge states to annihilate in new energy bands. Furthermore, when considering the existence of defects in the system, we found that when the strength of the defects are small, the edge state produces small fluctuations, but it can be clearly distinguished, indicating its robustness. When the strength of the defect exceeds the threshold, the edge state and energy band cause irregular fluctuations, allowing the edge state to integrate into the energy band. Our research results have important theoretical value and practical significance, and can be applied in quantum optics and quantum information processing in the future.