We introduce a multipartite communication scheme, with the aim to enable the senders to remotely and obliviously provide the receivers with an arbitrary amount of multipartite entanglement. The scheme is similar to remote state preparation (RSP). However, we show that even though the receivers are restricted to local unitary operations, the required resources for remote entanglement preparation are less than for RSP. In order to do so we introduce a canonical form of arbitrary multipartite pure states describing an arbitrary number of qubits. Moreover, we show that if the receivers are enabled to perform arbitrary local operations and classical communication, the required resources can drastically be reduced. We employ this protocol to derive robust entanglement purification protocols for arbitrary pure states and show that it can also be used for sending classical information.
Quantum secure communications could securely transmit quantum information by using quantum resource. Recently, novel applications such as bidirectional and asymmetric quantum protocols have been developed. \n \nIn this paper, we propose a new method for generating entanglement which is highly useful for multiparty quantum communications such as teleportation and Remote State Preparation (RSP). As one of its applications, we propose a new type of quantum secure communications, i.e. cyclic RSP protocols. Starting from a four-party controlled cyclic RSP protocol of one-qubit states, we show that this cyclic protocol can be generalized to a multiparty controlled cyclic RSP protocol for preparation of arbitrary qubit states. We point out that previous bidirectional and asymmetric protocols can be regarded as a simpler form of our cyclic RSP protocols.
We study the following task: Alice is given a classical description of a rank-
k projector
P on
Cd, and Alice and Bob want to prepare the quantum state
P/k on Bob's side using shared entanglement and classical communication. The general form of this task is known as remote state preparation (RSP). We give nearly-matching lower and upper bounds for the entanglement cost and communication cost for RSP of the states
P/k. Ours are the first nearly matching upper and lower bounds for RSP of mixed states, and in the special case of pure states, our lower bound outperforms the best previously known lower bound. Our results show that any pure entangled state that can be used to do RSP of these states with
o(d) bits of communication, can distill
logd ebits of entanglement, and conversely, any state that can distill
logd ebits of entanglement can be used to do RSP of these states efficiently. As applications of our results, we rederive a previously-known incompressibility result for states of the form
P/k, and give a new entanglement-assisted communication protocol for the equality function that uses
21logn+O(1) many ebits, and
O(1) communication.
Quantum teleportation uses prior shared entanglement and classical communication to send an unknown quantum state from one party to another. Remote state preparation (RSP) is a similar distributed task in which the sender knows the entire classical description of the state to be sent. (This may also be viewed as the task of nonoblivious compression of a single sample from an ensemble of quantum states.) We study the communication complexity of approximate RSP (ARSP) in which the goal is to prepare an approximation of the desired quantum state. Jain (Quant. Inf. & Comp., 2006) showed that the worst-case communication complexity of ARSP can be bounded from above in terms of the maximum possible information in an encoding. He also showed that this quantity is a lower bound for communication complexity of (exact) remote state preparation. In this paper, we tightly characterize the worst-case and average-case communication complexity of remote state preparation in terms of nonasymptotic information-theoretic quantities. We also show that the average-case communication complexity of RSP can be much smaller than the worst-case one. In the process, we show that
n bits cannot be communicated with less than
n transmitted bits in local operations and classical communication protocols. This strengthens a result due to Nayak and Salzman (J. ACM, 2006) and may be of independent interest.
In this paper, two efficient proposals are presented by using maximal slice states and orthogonal measurement basis to realize the joint remote state preparation (RSP) of two-qubit and three-qubit states, respectively. Furthermore, this kind of joint RSP schemes could be generalized to the case of arbitrary multi-qubit states, which can be transmitted from two senders to one receiver with the supervision of one manager. The successful probability of this joint RSP scheme is always equal to 100% in spite of that quantum channel is composed of non-maximally entangled states.
Remote state preparation (RSP) provides a useful way of transferring quantum information between two distant nodes based on the previously shared entanglement. In this paper, we study RSP of an arbitrary single-photon state in two degrees of freedom (DoFs). Using hyper-entanglement as a shared resource, our first goal is to remotely prepare the single-photon state in polarization and frequency DoFs and the second one is to reconstruct the single-photon state in polarization and time-bin DoFs. In the RSP process, the sender will rotate the quantum state in each DoF of the photon according to the knowledge of the state to be communicated. By performing a projective measurement on the polarization of the sender’s photon, the original single-photon state in two DoFs can be remotely reconstructed at the receiver’s quantum systems. This work demonstrates a novel capability for longdistance quantum communication.