Abstract Multipartite quantum steering has important application in quantum information processing. Here we study the influence of thermal noise on the collective quantum steering and genuine tripartite steering in a system of four-level inverted Y-type atoms, in which the atomic coherence is initially prepared and the cavity is coupled to a thermal reservoir. It is found that for the cases of the balanced and unbalanced cavity losses, the thermal noise plays a positive role in realizing the collective steering. However the case is different for the genuine tripartite steering effect. For the case of either balanced or unbalanced cavity losses, the thermal noise would destroy genuine tripartite steering effect and reduce the parameter region of genuine tripartite steering. The thermal noise plays a negative role in realizing genuine tripartite steering. Specially, it is verified that the genuine tripartite steering does not reject the bipartite steering, which is very different from the collective quantum steering requiring no bipartite steering. The present scheme may provide some help for potential applications such as quantum communication.
Abstract Multipartite quantum steering has important application in quantum information processing. Here we study the influence of thermal noise on the collective quantum steering and genuine tripartite steering in a system of four-level inverted Y-type atoms, in which the atomic coherence is initially prepared and the cavity is coupled to a thermal reservoir. It is found that for the cases of the balanced and unbalanced cavity losses, the thermal noise plays a positive role in realizing the collective steering. However the case is different for the genuine tripartite steering effect. For the case of either balanced or unbalanced cavity losses, the thermal noise would destroy genuine tripartite steering effect and reduce the parameter region of genuine tripartite steering. The thermal noise plays a negative role in realizing genuine tripartite steering. Specially, it is verified that the genuine tripartite steering does not reject the bipartite steering, which is very different from the collective quantum steering requiring no bipartite steering. The present scheme may provide some help for potential applications such as quantum communication.
The influence of thermal noise on bipartite and tripartite quantum steerings induced by a short laser pulse in a hybrid three-mode optomechanical system is investigated. Explicit analytical expressions are derived for the bipartite and tripartite steering parameters and the concept of collective tripartite quantum steering is explored. Tripartite steering of a mode is said to be the collective tripartite steering if it exists in the absence of all the bipartite steerings of the mode. It is found that both bipartite and tripartite steering parameters are sensitive functions of the initial state of the modes and distinctly different steering behaviour could be observed depending on whether the modes were initially in a thermal state or not. The collective steering can be achieved for the modes initially prepared in a thermal state. We find that the initial thermal noise is more effective in destroying the bipartite rather than the tripartite steering which, on the other hand, can persist even for a large thermal noise. For the initial vacuum state of a mode which is steered by the remaining modes, the tripartite steering exists over the entire interaction time even if the steering modes are in very noisy thermal states. There is no collective steering possible for the cavity and atomic modes, but the mirror mode can be collectively steered by the other modes although it is limited to long interaction time. When the steered mode is initially in a thermal state, it can be collectively steered by the other modes. There are thresholds for the average number of the thermal photons above which the existing tripartite steering appears as the collective steering. Finally, we point out that the collective steering may provide a resource in a hybrid quantum network for one-sided device-independent quantum secret sharing.
The influence of thermal noise on bipartite and tripartite quantum steering induced by a short laser pulse in a hybrid three-mode optomechanical system is investigated. The calculation is carried out under the bad cavity limit, the adiabatic approximation of a slowly varying amplitude of the cavity mode, and with the assumption of driving the cavity mode with a blue detuned strong laser pulse. Under such conditions, explicit expressions of the bipartite and tripartite steering parameters are obtained, and the concept of collective tripartite quantum steering, recently introduced by He and Reid [Phys. Rev. Lett. 111, 250403 (2013)], is clearly explored. It is found that both bipartite and tripartite steering parameters are sensitive functions of the initial state of the modes and distinctly different steering behavior could be observed depending on whether the modes were initially in a thermal state or not. For the modes initially in a vacuum state, the bipartite and tripartite steering occur simultaneously over the entire interaction time. This indicates that collective tripartite steering cannot be achieved. The collective steering can be achieved for the modes initially prepared in a thermal state. We find that the initial thermal noise is more effective in destroying the bipartite rather than the tripartite steering which, on the other hand, can persist even for a large thermal noise. For the initial vacuum state of a steered mode, the tripartite steering exists over the entire interaction time even if the steering modes are in very noisy thermal states. When the steered mode is initially in a thermal state, it can be collectively steered by the other modes. There are thresholds for the average number of the thermal photons above which the existing tripartite steering appears as the collective steering. Finally, we point out that the collective steering may provide a resource in a hybrid quantum network for quantum secret sharing protocol.
Multipartite quantum steering, a unique resource for asymmetric quantum network information tasks, is very fragile to the inevitable decoherence, which makes it useless for practical purposes. It is thus of importance to understand how it decays in the presence of noise channels. We study the dynamic behaviors of genuine tripartite steering, reduced bipartite steering, and collective steering of a generalized three-qubit W state when only one qubit interacts independently with the amplitude damping channel (ADC), phase damping channel (PDC) or depolarizing channel (DC). Our results provide the region of decoherence strength and state parameters that each type of steering can survive. The results show that these steering correlations decay the slowest in PDC and some non-maximally entangled states more robust than the maximally entangled ones. Unlike entanglement and Bell nonlocality, the thresholds of decoherence strength that reduced bipartite steering and collective steering can survive depend on the steering direction. In addition, we find that not only one party can be steered by a group system, but also two parties can be steered by a single system. There is a trade-off between the monogamy relation involving one steered party and two steered parties. Our work provides comprehensive information about the effect of decoherence on multipartite quantum steering, which will help to realize quantum information processing tasks in the presence of noise environments.
Abstract We present to use the thermal noise as an effective way to manipulate the direction of Einstein–Podolsky–Rosen (EPR) steering. In particular, a system of three-level cascade laser is under our consideration, in which the atoms are prepared in an initial superposition of the upper excited level and ground level and the cavity modes are damped by the thermal bath. It is found that the thermal noise plays a constructive role in realizing the one-way EPR steering and expanding the parameter region of the steady-state asymmetric steering. In the absence of the thermal noise, two-way steering mainly occurs due to the injected atomic coherence that is quite helpful for entanglement enhancement. Surprisingly, when the thermal noise is involved, the one-way steering substitutes for two-way steering and it can be obtainable in most parameter region. Actually, the thermal noise significantly increases the mean number of the emitted photon pairs and enlarges the intensity difference between two cavity modes, which leads to the striking asymmetry in the mean photon numbers and then induces the unidirectional steerability from the mode generated by the upper transition to the mode in the low transition. The present scheme may provide a resource in a long-distance quantum network for quantum secret sharing protocol.
Multipartite quantum entanglement is a key resource for ensuring security in quantum network. We show that by using a unified parameter in terms of reduced noise variances one can determine different types of tripartite entanglement of a given state generated in a hybrid optomechanical system, where an atomic ensemble is located inside a single-mode cavity with a movable mirror, with different thresholds for each type. In particular, the special quantum states which allow both entanglement and steering genuinely shared among atom-light-mirror modes can be observed, even though there is no direct interaction between the mirror and the atomic ensemble. We further show the robustness against mechanical thermal noise and damping, the relaxation time of atomic ensemble, as well as the effect of gain factors involved in the criteria. Our analysis provides an experimentally achievable method to determine the type of tripartite quantum correlation in a way.
Abstract We show that thermal noise could play a positive role in generating one-way Einstein–Podolsky–Rosen (EPR) steering of two cavity fields dispersively interacting with a single four-level atom, each of which is independently coupled to a thermal reservoir. In the low- Q and weak Raman transition regimes, two output fields exhibit asymmetric EPR steering and the steering direction could be easily controlled by adjusting the mean photon numbers of the thermal reservoirs and the decay rates of cavities. Striking features are present in our scheme. First, one-way EPR steering is achieved by using the couplings of the cavities with the heat baths, which sheds light on the quantum state manipulation in the presence of decoherence. Second, the obtainable EPR steering occurs between the cavity fields in the low- Q regime, which relaxes the constraints on the use of good cavities and so makes our scheme more practical. Third, the correlation properties of the output modes are considered, which can be measured more conveniently and will be more applicable to implement a range of quantum information processing.