Deterministic secure quantum communication against collective-dephasing noise by using EPR pairs and auxiliary photons

A deterministic secure quantum communication against collective-dephasing noise is proposed. Alice constructs two sets of three-photon bases with EPR (Einstein-Podolsky-Rosen) pairs in the state |Ψ⁺〉 or |Ψ^-〉 and auxiliary single photons in the state |H〉. And then she sends them to Bob. Bob can get the secret message by his single-photon measurement outcomes and two public message strings from Alice if the quantum channel is secure. The scheme does not need photon storing technique and only single-photon measurement is necessary.     

Bidirectional Controlled Quantum Teleportation of Three-Qubit State by a New Entangled Eleven-Qubit State

In this paper, an improved controlled bidirectional quantum teleportation protocol of the special three-qubit state is proposed. In a little bit more detail, under the control of the third supervisor Charlie, Alice wants to send one special three-qubit entangled state to Bob, and at the meantime, Bob also wants to transmit another special three-qubit entangled state to Alice. In other words, both Alice and Bob can be the sender and receiver simultaneously. To achieve this aim, a specific eleven-qubit entangled state is shared among Alice, Bob and Charlie in advance acting as the quantum channel. Then, Alice and Bob first implement the GHZ-state measurement and Bell-state measurement respectively, and following Charlie’s single-qubit measurement. Finally, upon the foregoing measurement results, Alice and Bob can respectively implement the specific unitary operators on their local particles to recover the initial state transmitted by the other.

     

Deterministic Secure Quantum Communication and Authentication Protocol based on Extended GHZ-W State and Quantum One-time Pad

A deterministic secure quantum communication and authentication protocol based on extended GHZ-W state and quantum one-time pad is proposed. In the protocol, state |φ^?〉 is used as the carrier. One photon of |φ^?〉 state is sent to Alice, and Alice obtains a random key by measuring photons with bases determined by ID. The information of bases is secret to others except Alice and Bob. Extended GHZ-W states are used as decoy photons, the positions of which in information sequence are encoded with identity string ID of the legal user, and the eavesdropping detection rate reaches 81%. The eavesdropping detection based on extended GHZ-W state combines with authentication and the secret ID ensures the security of the protocol.     

Spin-orbit hybrid entanglement quantum key distribution scheme

We propose a novel quantum key distribution scheme by using the SAM-OAM hybrid entangled state as the physical resource.To obtain this state,the polarization entangled photon pairs are created by the spontaneous parametric down conversion process,and then,the q-plate acts as a SAM-to-OAM transverter to transform the polarization entangled pairs into the hybrid entangled pattern,which opens the possibility to exploit the features of the higher-dimensional space of OAM state to encode information.In the manipulation and encoding process,Alice performs the SAM measurement by modulating the polarization stateπ lθx on one photon,whereas Bob modulates the OAM sector state lx' on the other photon to encode his key elements using the designed holograms which is implemented by the computer-controlled SLM.With coincidence measurement,Alice could extract the key information.It is showed that N-based keys can be encoded with each pair of entangled photon,and this scheme is robust against Eve’s individual attack.Also,the MUBs are not used.Alice and Bob do not need the classical communication for the key recovery.     

Bidirectional Quantum Controlled Teleportation via Five-Qubit Cluster State

A theoretical scheme for bidirectional quantum controlled teleportation is presented using the entanglement property of five-qubit cluster state. This means that Alice wants to transmit a entangled state of particle a to Bob and Bob wants to transmit a entangled state of particle b to Alice via the control of the supervisor Charlie.     

Quantum Authencryption with Two-Photon Entangled States for Off-Line Communicants

In this paper, a quantum authencryption protocol is proposed by using the two-photon entangled states as the quantum resource. Two communicants Alice and Bob share two private keys in advance, which determine the generation of two-photon entangled states. The sender Alice sends the two-photon entangled state sequence encoded with her classical bits to the receiver Bob in the manner of one-step quantum transmission. Upon receiving the encoded quantum state sequence, Bob decodes out Alice’s classical bits with the two-photon joint measurements and authenticates the integrity of Alice’s secret with the help of one-way hash function. The proposed protocol only uses the one-step quantum transmission and needs neither a public discussion nor a trusted third party. As a result, the proposed protocol can be adapted to the case where the receiver is off-line, such as the quantum E-mail systems. Moreover, the proposed protocol provides the message authentication to one bit level with the help of one-way hash function and has an information-theoretical efficiency equal to 100 %.     

Teleportation of the one-qubit state with environment-disturbed recovery operations

We study standard protocol \hbox{$\mathcal{P}_0$} ??₀ for teleporting the one-qubit state with both the transmission process of the two qubits constitute the quantum channel and the recovery operations performed by Bob disturbed by the decohering environment. The results revealed that Bob’s imperfect operations do not eliminate the possibility of nonclassical teleportation fidelity provided he shares an ideal channel state with Alice, while the transmission process is constrained by a critical time t _0, ? c longer than which will result in failure of \hbox{$\mathcal{P}_0$} ??₀ if the two qubits are corrupted by the decohering environment. Moreover, we found that under the condition of the same decoherence rate γ, the teleportation protocol is significantly more fragile when it is executed under the influence of the noisy environment than those under the influence of the dissipative and dephasing environments.     

Analysis of Counterfactual Quantum Certificate Authorization

A counterfactual quantum certificate authorization protocol was proposed recently (Shenoy et al., Phys. Rev. A 89, 052307 (20)), in which a trusted third party, Alice, authenticates an entity Bob (e.g., a bank) that a client Charlie wishes to securely transact with. However, this protocol requires a classical authenticated channel between Bob and Charlie to prevent possible attacks from the third party Alice, which is in conflict with the task of certificate authorization in the sense that Bob and Charlie can establish an unconditionally-secure key by a quantum key distribution protocol if there is a classical authenticated channel between them and hence securely transact with each other even without the assistance of the third party Alice.     

Intercept-resend attack on six-state quantum key distribution over collective-rotation noise channels

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 interceptresend 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.     

Differential phase shift quantum key distribution

A novel quantum cryptography scheme is proposed, in which a single photon is prepared in a linear superposition state of three basis kets. A photon split to three pulses is sent from Alice to Bob, where the phase difference between sequential two pulses carries bit information. Bob measures the phase difference by passive differential phase detection. This scheme is suitable for fiber transmission systems and offers a key creation efficiency higher than conventional fiber-based BB84.     

基于cluster态的信道容量可控的可控量子安全直接通信方案

提出了一种基于五粒子cluster态的信道容量可控的可控量子安全直接通信方案.通信三方利用五粒子cluster态自身的粒子分布情况,结合诱骗光子,对粒子分别做Z基单粒子测量和Bell基测量,便可完成信道的第一次安全性检测.通信控制方Cindy通过对手中的粒子序列随机选用测量基(Z基或者X基)测量来决定信道容量,并通过经典信道公布结果.发送方Alice将要发送的信息以及校检信息用于对手中的粒子序列进行幺正操作编码,并插入诱骗光子后将编码后的粒子序列发给接收方Bob并通过经典信道告知其诱骗光子的位置信息.Bob接收到粒子序列后,按照经典信道Alice发送的信息,结合Cindy公布的信息,剔除诱骗光子后按照一定的规则对手中的两组粒子序列进行Bell基测量,便可解码完成第二次安全性检测以及得到Alice发送的信息.通过对五粒子cluster态的纠缠结构性质进行分析,阐明了五粒子cluster态在该方案中所表现出的特点的物理缘由.结果表明,只需变化测量基的规则和用于编码的粒子,可以将该方案推广成可控双向量子安全直接通信.     

A generalized complexity measure based on Rényi entropy

Phase drift is an inherent problem in one-way phase-encoded quantum key distribution (QKD) systems. Although combining passive with active phase compensation (APC) processes can effectively compensate for the phase drift, the security problems brought about by these processes are rarely considered. In this paper, we point out a security hole in the APC process and put forward a corresponding attack scheme. Under our proposed attack, the quantum bit error rate (QBER) of the QKD can be close to zero for some conditions. However, under the same conditions the ratio r of the key “0” and the key “1” which Bob (the legal communicators Alice and Bob) gets is no longer 1:1 but 2:1, which may expose Eve (the eavesdropper). In order to solve this problem, we modify the resend strategy of the attack scheme, which can force r to reach 1 and the QBER to be lower than the tolerable QBER.     

Side Channel Passive Quantum Key Distribution with One Uninformative State

In most of quantum key distribution schemes, real random number generators are required on both sides for preparation and measurement bases choice. In this paper, via entangled photon pairs, we present a side channel passive quantum key distribution scheme, in which random number generator is unneeded on the receiver side. On the sender Alice side, along with massive of signal photons, small amount of uninformative photons are randomly sent to her partner Bob for eavesdropper-presence testing and error estimation. While on the other side channel, without using random number generator Bob do not actively measure the income signals randomly in two non-orthogonal bases. Instead, he just passively register photon click events, in two settled symmetric (i.e.X) bases, and the raw key(click events) is the probable outcomes of a special quantum measurement module constructed by Alice and Bob. Further, security analysis and formulas of security bounds for this scheme is also investigated under reasonable assumptions. Our work shows that the uninformative state employed in this paper is powerful to fight against eavesdropper Eve.     

Quantum Key Distribution Using a <Emphasis Type="Italic">χ</Emphasis>-Type State

By swapping the entanglement of χ-type state, we propose a quantum key distribution protocol, in which only Alice needs to prepare χ-type states and transmit a particle sequence. Both Alice and Bob need to perform χ-type state measurements.     

Controlled Cyclic Remote Preparation of an Arbitrary Single-Qudit State by Using a Seven-Qudit Cluster State as the Quantum Channel

We present a protocol for controlled cyclic remote preparation of an arbitrary single-qudit state via a seven-qudit cluster state. In the protocol, Alice can help the remote agent Bob prepare an arbitrary single-qudit state, Bob can help the agent Charlie prepare an arbitrary single-qudit state and at the same time Charlie can help Alice prepare an arbitrary single-qudit state under the controller David’s control. Alice, Bob and Charlie first perform positive operator-valued measurement (POVM) on their entangled particles according to the information of the prepared state, then perform generalized X-basis measurement. The controller performs generalized X-basis measurement on his entangled particle. The arbitrary single-qudit states can be cyclic remote prepared under the controller’s control. The protocol is more convenient in application since it only requires single-particle measurement and single-particle unitary operations for controlled cyclic remote preparation of the single-qudit states.

     

三粒子GHZ态的量子信息分离方案(英文)

提出一个用GHZ态作为量子信道分离类GHZ态的方案.如果发送者Alice预先知道原量子态,Alice执行两量子比特投影测量后,接收者Bob和Charlie一起合作能恢复初态.我们计算了这个方案成功的几率和消耗的经典信息.一般地,Alice能成功地分离量子态的几率是1/4和消耗的经典信息是3/4经典比特.然而,在五种特殊情形下,消耗一些多余经典信息后,成功的几率能达到1/2甚至1.     

Two Ways of Robust Quantum Dialogue by Using Four-Qubit Cluster State

In this paper, we present a scheme for quantum dialogue by using a four-qubit cluster state as quantum channel.The scheme has two cases: Case 1, Sender Alice and receiver Bob share information using an orderly sequence of entangled state as quantum channel which was prepared by Alice. This case is achieved as follows: The two sides agreed to encode quantum state information, then Alice perform a bell state measurement for quantum information which has been encoded. This will convey the information to Bob, then Bob measuring his own qubits, through the analysis of the measurement results of Alice and Bob, Bob can obtain quantum information. For case 2, four-qubit cluster state and quantum state information is transmitted to form a total quantum system. In the Case 2 scenario, Alice and Bob perform bell state measurements for part of the qubits, and tell the measurement result to each other through the classical channel. Finally, according to the measurement result, Alice and Bob operate an appropriate unitary transformation, as a result, Alice’s qubit will be renewed upon Bob’s measurements, and also, Bob’s qubit will be renewed upon Alice’s measurements. Thus, a bidirectional quantum dialogue is achieved. After analysis, this scheme has high security by taking certain eavesdropping attacks into account. There is therefore a certain reference value to the realization of quantum dialogue.     

A scheme for secure direct communication using EPR pairs and teleportation

A novel scheme for secure direct communication between Alice and Bob is proposed, where there is no need for establishing a shared secret key. The communication is based on Einstein-Podolsky-Rosen (EPR) pairs and teleportation between Alice and Bob. After insuring the security of the quantum channel (EPR pairs), Bob encodes the secret message directly on a sequence of particle states and transmits them to Alice by teleportation. In this scheme teleportation transmits Bobs message without revealing any information to a potential eavesdropper. Alice can read out the encoded messages directly by the measurement on her qubits. Because there is not a transmission of the qubit which carries the secret message between Alice and Bob, it is completely secure for direct secret communication if perfect quantum channel is used.Received: 17 March 2004, Published online: 30 September 2004PACS: 03.67.Dd Quantum cryptography - 03.67.Hk Quantum communicationF.L. Yan: Present address: Department of Physics, Hebei Normal University, Shijiazhuang 050016, P.R. China     

An efficient quantum key distribution protocol with orthogonal product states

An efficient quantum key distribution (QKD) protocol with orthogonal product states in the 3 \otimes 3 Hilbert space is presented. The sender, Alice, disorders the orthogonal product state sequence and sends it to Bob. After Alice has published the matching information of the particle sequence, Bob recovers the correct correspondences and makes an orthogonal measurement on the orthogonal product states to obtain the information sent by Alice. Finally, security analysis is also made.     

Bidirectional Quantum Controlled Teleportation via a Six-Qubit Entangled State

A new application of six-qubit entangled state introduced by Chen et al. (Phys. Rev. A 74, 032324, 2006) is studied for the bidirectional quantum controlled teleportation. In our scheme, a six-qubit entangled state is shared by Alice, Bob and Charlie, Alice and Bob can transmit simultaneously an arbitrary single-qubit state to each other under the control of the supervisor Charlie.