Collective-noise Channel Research Articles

Quantum private information retrieval over a collective noisy channel

Quantum Private Information Retrieval (QPIR) allows a user (Alice) to retrieve a database item from the database owned by the database holder (Bob) in such a way that Alice can query only the database item she wants, but cannot get other items, and Bob does not know which item Alice queries. However, the real quantum channel between Alice and Bob is noisy, and the noise may result in not only the chance that Alice obtains a false item, but also that both parties may cheat by camouflaging themselves with noise. In this paper, we use the decoherence-free subspace (DFS) for QPIR, which we call DFS-QPIR. The DFS-QPIR protocol removes the effect of the channel noise on the errors in the retrieved item so that two parties cannot cheat by replacing the noisy channel with a noiseless one. It can work over a collective noisy channel while retaining high reliability, database security and user privacy simultaneously. While only the collective unitary noise is taken into account, the proposed DFS-QPIR protocol can be straightforwardly extended to more general collective noise channel.

Quantum Key Agreement Protocols with GHZ States Under Collective Noise Channels

Quantum Key Agreement Protocols with GHZ States Under Collective Noise Channels

Faithful entanglement distribution using quantum multiplexing in noisy channel

Quantum multiplexing provides us with a powerful approach that can distribute entanglement using only a single photonic pulse to interact with remote quantum memories. In common entanglement distribution protocols, the entanglement purification is often exploited if the distributed entanglement is degraded by the channel noise. In this protocol, we propose a faithful entanglement distribution protocol using quantum multiplexing of photon in a collective noise channel. By designing the encoding and decoding setup, our protocol can resist the collective noise. When the protocol is successful, the parties can obtain two pairs of maximally entangled states. When the protocol fails, the parties can still obtain one pair of maximally entangled state. Our protocol does not require the entanglement purification, so that it is more efficient. The above advantages enable our protocol to have important application potential in the future quantum communication field.

Quantum key agreement with Bell states and Cluster states under collective noise channels

The collective noises, which include the collective-dephasing noise and the collective-rotation noise, are the topical noises in quantum key agreement (QKA). How to eliminate the influence of the collective noises on quantum communication is a problem to be solved urgently. In this paper, based on logical quantum states, by using controlled-Z, controlled-NOT and unitary operations, two QKA protocols which can be immune to the collective-dephasing noise and the collective-rotation noise are proposed, respectively. The security analysis indicates that these two protocols can resist participant attack and outsider attacks which include Trojan-horse attacks, intercept-resend attack, measure-resend attack and entangle-measure attack. By comparing with the proposed two-party QKA protocols against the collective noises, it is clear that our protocols are more efficient.

Authenticated semiquantum dialogue with secure delegated quantum computation over a collective noise channel

Semiquantum communication permits a communication party with only limited quantum ability (i.e., “classical” ability) to communicate securely with a powerful quantum counterpart and will obtain a significant advantage in practice when the completely quantum world has not been built up. At present, various semiquantum schemes for key distribution, secret sharing and secure communication have been proposed. In a quantum dialogue (QD) scenario, two communicants mutually transmit their respective secret messages and may have equal power (such as two classical parties). Based on delegated quantum computation model, this work extends the original semiquantum model to the authenticated semiquantum dialogue (ASQD) protocols, where two “classical” participants can mutually transmit secret messages without any information leakage and quantum operations are securely delegated to a quantum server. To make the proposed ASQD protocols more practical, we assume that the quantum channel is a collective noise channel and the quantum server is untrusted. The security analysis shows that the proposed protocols are robust even when the delegated quantum server is a powerful adversary.

Robust Multi-party Quantum Private Comparison Protocols Against the Collective Noise Based on Three-Qubit Entangled States

Recently, Ye and Ji constructed a multi-party quantum private comparison (MQPC) protocol with Bell entangled states (Sci. China Phys. Mech. Astron. 60(9), 090312, 2017). However, this protocol is only workable over an ideal quantum channel. In this paper, we take the collective noise channel into account and generalize Ye and Ji’s protocol into the ones against the collective-dephasing noise and the collective-rotation noise, respectively. Concretely, we use three-qubit entangled states instead of Bell states as the initial quantum states and employ the corresponding logical qubits immune to the collective noise instead of the physical qubits as the travelling particles. The output correctness and the security of the proposed robust MQPC protocols can be guaranteed.

Two-party quantum key agreement protocols under collective noise channel

Recently, quantum communication has become a very popular research field. The quantum key agreement (QKA) plays an important role in the field of quantum communication, based on its unconditional security in terms of theory. Among all kinds of QKA protocols, QKA protocols resisting collective noise are widely being studied. In this paper, we propose improved two-party QKA protocols resisting collective noise and present a feasible plan for information reconciliation. Our protocols’ qubit efficiency has achieved 26.67%, which is the best among all the two-party QKA protocols against collective noise, thus showing that our protocol can improve the transmission efficiency of quantum key agreement.

Multi-server blind quantum computation over collective-noise channels

Blind quantum computation (BQC) enables ordinary clients to securely outsource their computation task to costly quantum servers. Besides two essential properties, namely correctness and blindness, practical BQC protocols also should make clients as classical as possible and tolerate faults from nonideal quantum channel. In this paper, using logical Bell states as quantum resource, we propose multi-server BQC protocols over collective-dephasing noise channel and collective-rotation noise channel, respectively. The proposed protocols permit completely or almost classical client, meet the correctness and blindness requirements of BQC protocol, and are typically practical BQC protocols.

Quantum error rejection and fault tolerant quantum communication

Quantum communication utilizes the quantum state as information carrier. The transmission of quantum states is therefore a precondition for various quantum communication protocols. Photons play a central role in quantum communication since they are fast, cheap, easy to control and interact weakly with the environment. However, the widely used polarization degree of freedom of photons is vulnerable to the noise during the transmission. In this article, we review two main methods to deal with the channel noise, i.e., the quantum error rejection scheme and fault tolerant quantum communication. To transmit an arbitrary single-photon state, Li and Deng proposed two faithful state transmission schemes only by resorting to passive linear optics. The success probability can be (2N+1-1)/2N+1 by introducing a wave splitter composed of N unbalance interferometers. Compared with other quantum error rejection schemes, these two scheme are practical both in maneuverability and resource consumption. They are not only suitable for single-photon pure state transmission but also able to be used for transmitting mixed state, which makes them useful for one-way quantum communication. The success probability of error rejection is usually less than 100% since some error cases are rejected. To realize complete fault tolerant quantum communication, decoherence free subspace can be used to encode quantum information. In 2008, Li et al. proposed two efficient quantum key distribution schemes over two different collective-noise channels. The noiseless subspaces are made up of two Bell states and the spatial degree of freedom is introduced to form two nonorthogonal bases. Although entangled states are employed, only single-photon measurements are required to read the information. Later, the scheme is generalized to an efficient one which transmits n-1 bits information via n Einstein-Podolsky-Rosen pairs and many fault tolerant quantum communication schemes were proposed. We compare the practicality of different anti-noise schemes based on maneuverability and resource consumption and a perspective of these two research directions is given in the last section.

Self-error-rejecting photonic qubit transmission in polarization-spatial modes with linear optical elements

We present an original self-error-rejecting photonic qubit transmission scheme for both the polarization and spatial states of photon systems transmitted over collective noise channels. In our scheme, we use simple linear-optical elements, including half-wave plates, 50:50 beam splitters, and polarization beam splitters, to convert spatial-polarization modes into different time bins. By using postselection in different time bins, the success probability of obtaining the uncorrupted states approaches 1/4 for single-photon transmission, which is not influenced by the coefficients of noisy channels. Our self-error-rejecting transmission scheme can be generalized to hyperentangled N-photon systems and is useful in practical high-capacity quantum communications with photon systems in two degrees of freedom.

Efficient and Secure Authenticated Quantum Dialogue Protocols over Collective-Noise Channels**Supported by the Foundation and Frontier Research Program of Chongqing Science and Technology Commission of China under Grant No cstc2016jcyjA0571.

Based on the deterministic secure quantum communication, we present a novel quantum dialogue protocol without information leakage over the collective noise channel. The logical qubits and four-qubit decoherence-free states are introduced for resisting against collective-dephasing noise, collective-rotation noise and all kinds of unitary collective noise, respectively. Compared with the existing similar protocols, the analyses on security and information-theoretical efficiency show that the proposed protocol is more secure and efficient.

Multi-photon self-error-correction hyperentanglement distribution over arbitrary collective-noise channels

We present a self-error-correction spatial-polarization hyperentanglement distribution scheme for N-photon systems in a hyperentangled Greenberger–Horne–Zeilinger state over arbitrary collective-noise channels. In our scheme, the errors of spatial entanglement can be first averted by encoding the spatial-polarization hyperentanglement into the time-bin entanglement with identical polarization and defined spatial modes before it is transmitted over the fiber channels. After transmission over the noisy channels, the polarization errors introduced by the depolarizing noise can be corrected resorting to the time-bin entanglement. Finally, the parties in quantum communication can in principle share maximally hyperentangled states with a success probability of 100%.

Deterministic distribution of four-photon Dicke state over an arbitrary collective-noise channel with cross-Kerr nonlinearity.

We present two deterministic quantum entanglement distribution protocols for a four-photon Dicke polarization entangled state resorting to the frequency and spatial degrees of freedom, which are immune to an arbitrary collective-noise channel. Both of the protocols adopt the X homodyne measurement based on the cross-Kerr nonlinearity to complete the task of the single-photon detection with nearly unit probability in principle. After the four receivers share the photons, they add some local unitary operations to obtain a standard four-photon Dicke polarization entangled state.

Intercept-resend attack on six-state quantum key distribution over collective-rotation noise channels**Project supported by the South African Research Chair Initiative of the Department of Science and Technology and National Research Foundation.

We investigate the effect of collective-rotation noise on the security of the six-state quantum key distribution. We study the case where the eavesdropper, Eve, performs an intercept-resend attack on the quantum communication between Alice, the sender, and Bob, the receiver. We first derive the collective-rotation noise model for the six-state protocol and then parameterize the mutual information between Alice and Eve. We then derive quantum bit error rate for three intercept-resend attack scenarios. We observe that the six-state protocol is robust against intercept-resend attacks on collective rotation noise channels when the rotation angle is kept within certain bounds.

Fault-tolerant Remote Quantum Entanglement Establishment for Secure Quantum Communications

This work presents a strategy for constructing long-distance quantum communications among a number of remote users through collective-noise channel. With the assistance of semi-honest quantum certificate authorities (QCAs), the remote users can share a secret key through fault-tolerant entanglement swapping. The proposed protocol is feasible for large-scale distributed quantum networks with numerous users. Each pair of communicating parties only needs to establish the quantum channels and the classical authenticated channels with his/her local QCA. Thus, it enables any user to communicate freely without point-to-point pre-establishing any communication channels, which is efficient and feasible for practical environments.

Deterministic error correction for nonlocal spatial-polarization hyperentanglement.

Hyperentanglement is an effective quantum source for quantum communication network due to its high capacity, low loss rate, and its unusual character in teleportation of quantum particle fully. Here we present a deterministic error-correction scheme for nonlocal spatial-polarization hyperentangled photon pairs over collective-noise channels. In our scheme, the spatial-polarization hyperentanglement is first encoded into a spatial-defined time-bin entanglement with identical polarization before it is transmitted over collective-noise channels, which leads to the error rejection of the spatial entanglement during the transmission. The polarization noise affecting the polarization entanglement can be corrected with a proper one-step decoding procedure. The two parties in quantum communication can, in principle, obtain a nonlocal maximally entangled spatial-polarization hyperentanglement in a deterministic way, which makes our protocol more convenient than others in long-distance quantum communication.

Heralded quantum repeater for a quantum communication network based on quantum dots embedded in optical microcavities

We propose a heralded quantum repeater protocol based on the general interface between the circularly polarized photon and the quantum dot embedded in a double-sided optical microcavity. Our effective time-bin encoding on photons results in the deterministic faithful entanglement distribution with one optical fiber for the transmission of each photon in our protocol, not two or more. Our efficient parity-check detector implemented with only one input-output process of a single photon as a result of cavity quantum electrodynamics makes the entanglement channel extension and entanglement purification in quantum repeater far more efficient than others, and it has the potential application in fault-tolerant quantum computation as well. Meanwhile, the deviation from a collective-noise channel leads to some phase-flip errors on the nonlocal electron spins shared by the parties and these errors can be depressed by our simplified entanglement purification process. Finally, we discuss the performance of our proposal, concluding that it is feasible with current technology.

Which verification qubits perform best for secure communication in noisy channel?

In secure quantum communication protocols, a set of single qubits prepared using 2 or more mutually unbiased bases or a set of $n$-qubit ($n\geq2$) entangled states of a particular form are usually used to form a verification string which is subsequently used to detect traces of eavesdropping. The qubits that form a verification string are referred to as decoy qubits, and there exists a large set of different quantum states that can be used as decoy qubits. In the absence of noise, any choice of decoy qubits provides equivalent security. In this paper, we examine such equivalence for noisy environment (e.g., in amplitude damping, phase damping, collective dephasing and collective rotation noise channels) by comparing the decoy-qubit assisted schemes of secure quantum communication that use single qubit states as decoy qubits with the schemes that use entangled states as decoy qubits. Our study reveals that the single qubit assisted scheme perform better in some noisy environments, while some entangled qubits assisted schemes perform better in other noisy environments. Specifically, single qubits assisted schemes perform better in amplitude damping and phase damping noisy channels, whereas a few Bell-state-based decoy schemes are found to perform better in the presence of the collective noise. Thus, if the kind of noise present in a communication channel (i.e., the characteristics of the channel) is known or measured, then the present study can provide the best choice of decoy qubits required for implementation of schemes of secure quantum communication through that channel.

Unconditionally Secure Quantum Communications Via Decoherence-Free Subspaces

We show how to use decoherence-free subspaces over collective-noise quantum channels to convey classical information in perfect secrecy. We argue that codes defined over decoherence-free subspaces are codes for quantum wiretap channels in which the gain of information by a non-authorized third part is zero. We also show that if some symmetry conditions are guaranteed, the maximum rate on which such secret communications take place is equal to the ordinary capacity of a quantum channel to convey classical information. As a consequence of these results, we show how some protocols for secure communication can be simplified, reducing significantly the number of communications performed.

An Efficient Quantum Private Comparison of Equality over Collective-Noise Channels

This article proposes a collective-noise resistant QPC protocol with the help of an almostdishonest third party (TP) who may try to perform any sort of attacks to derive participants’ private secrets except colluding with any participant. The proposed scheme has some considerable advantages over the state-of-the-art QPC protocols over collective-noise channels, where it does not require any pre-shared key between the participants (Alice and Bob). Nevertheless, the proposed scheme can resist Trojan horse attacks without consuming half of the transmitted qubits and any additional equipment (wavelength filter and PNS) support. As a consequence, the proposed QPC protocol can guarantee higher qubit efficiency as compared to the others over collective noise channels.