Noise is unavoidable in practice and its presence makes quantum protocols imperfect. In this paper we consider a way to cope with typical types of noise in joint remote preparation of an arbitrary 2-qubit state. The idea is to use nonmaximally (in stead of maximally) entangled states as the initial quantum channel. Because noise changes the initial quantum channel we can beforehand tailor it to be nonmaximally entangled by introducing free parameters which, depending on given types of noise, can be controlled so that due to the affect of noise the initial quantum channel becomes closest to the maximally entangled one, thus optimizing the performance of the joint remote state preparation protocol. The dependence of the optimal averaged fidelities on the strength of various types of noise is represented by phase diagrams that clearly separate the quantum domain from the classical one.
Quantum communication is one of the cutting-edge research areas today, where the scheme of Remote State Preparation (RSP) has caught significant attention of researchers. A number of different schemes of RSP have already been proposed so far. We propose here a hierarchical RSP protocol for sending a two-qubit entangled state using a seven-qubit highly entangled state derived from Brown et al. state. We have also studied here the effects of two well known noise models namely amplitude damping (AD) and phase damping (PD) that affect the quantum communication channel used for the protocol. An investigation on the variation of fidelity of the state with respect to the noise operator and the receiver is made. PD noise is found to affect the fidelity more than the AD noise and the higher power receiver, obtains the state with higher fidelity than the lower power receiver under the effect of noise. To the best of our knowledge, we believe that we have achieved the highest fidelity for the higher power receiver, 0.89 in the presence of maximum AD noise and 0.72 in the presence of maximum PD noise, compared to all the previously proposed RSP protocols in noisy environments. The study of noise is described in a very pedagogical manner for better understanding of the application of noise models to a communication protocol.
Abstract The inherent association between real quantum systems and their surrounding environment invariably results in decoherence, leading to the loss of entanglement. This diminution in entanglement coincides with a decline in the fidelity of transmitted information using the entangled quantum resource. This study scrutinizes the impact of the squeezed generalized amplitude damping (SGAD) channel on quantum Fisher information (QFI) parameters. The SGAD channel model, a versatile framework, is also employed to simulate other dissipative channels, including amplitude damping (AD) and generalized amplitude damping (GAD). Kraus operators facilitate the modeling of noisy channels. The results reveal that, within the SGAD channel, the QFI remains impervious to the squeezing variables (r and
Φ Φ ). In the GAD channel,
FθGAD F θ GAD undergoes enhancement to a constant value with an upswing in temperature (T), while the
ϕ ϕ parameter in the GAD channel,
FϕGAD F ϕ GAD , akin to the SGAD channel, surges around T = 2 before complete loss ensues. Concerning the AD channel, the
θ θ component of the QFI initially experiences decoherence with an augmentation in the AD noise parameter (
λ λ ). Subsequently, it is restored to its initial value with a further escalation in
λ λ . Conversely, the
ϕ ϕ component of the QFI in the AD channel experiences decoherence with an elevation in the AD noise parameter (
λ λ ).
In this paper, the technique of weak measurement is employed in order to enhance the fidelity of joint remote state preparation (JRSP) protocol under decoherence. We design a quantum circuit of joint remote preparation of a single-qubit state through a GHZ state. Then, we analytically derive the average fidelity of the JRSP protocol under four types of noise usually encountered in real-world implementations of quantum communication protocols, i.e. the phase-flip, depolarizing, amplitude-damping and bit-flip noise. Our study shows that the application of weak measurement and measurement reversal could enhance the average fidelity of the JRSP process under the influence of phase-flip, depolarizing, amplitude-damping noise for most values of the decoherence parameters. If the JRSP process suffers from the bit-flip noise, the weak measurement technique is not useful for increasing the average fidelity.
Squeezing of a thermal bath introduces features absent in an open quantum system interacting with an uncorrelated (zero squeezing) thermal bath. The resulting dynamics, governed by a Lindblad-type evolution, extends the concept of a generalized amplitude damping channel, which corresponds to a dissipative interaction with a purely thermal bath. Here we present the Kraus representation of this map, which we call the squeezed generalized amplitude damping channel. As an application of this channel to quantum information, we study the classical capacity of this channel.
We present a scheme for remote preparing a general two-particle state by two entangled states serving as the quantum communication channel. In this scheme, it is possible for the receiver to perfectly reconstruct the initial state that the sender hopes to prepare with the method of introducing an auxiliary qubit and postselection measurements in the situation of non-maximal entangled quantum channel. Furthermore, we investigate the influence of the dissipation factors on the processing of the remote state preparation when the entangled resources are in the Markovian and non-Markovian noisy environments. It is shown that the fidelity of remote state preparation is decreasing exponentially over time in Markovian environments and attenuating oscillatorily in non-Markovian. However, when the non-Markovian and the detuning conditions are satisfied simultaneously, the fidelity can be preserved at comparative high levels, effectively.