Nonlocal Advantage Of Quantum Coherence Research Articles

Suppressing the degeneration of quantum resources through coupling auxiliary qubits

The nonlocal advantage of quantum coherence (NAQC), quantum coherence (QC), and quantum entanglement are promising quantum resources to achieve various quantum information tasks. However, the decoherence of quantum resource is detrimental to the implementation of quantum information processing, and it brings enormous challenge to the application of quantum resource. Here, consider that Alice and Bob possess a two-qubit X state, and the two-qubit X state is composed of two atoms. Bob’s atom interacts with a reservoir, and Alice's atom is subjected to the influence of amplitude damping channel. We design an effective scheme by coupling auxiliary qubits with reservoir, and this scheme can significantly suppress the dissipation of the NAQC, QC, and quantum entanglement. The results reveal that the NAQC, QC, and quantum entanglement degenerate with the increase of time t in the strong coupling regime or weak coupling regime when absenting auxiliary qubits. If one adds some auxiliary qubits in the reservoir, these quantum resources can be strengthened both in the strong coupling regime and weak coupling regime. Auxiliary qubits can help us effectively resist the dissipation of these quantum resources. In comparison with the QC and quantum entanglement, the NAQC is most fragile and it is most vulnerable to the influences of reservoir and noise channel. One needs introduce more auxiliary qubits to suppress the dissipation of the NAQC, especially in the scenarios of the weak coupling regime and strong channel parameter. In this sense, our investigations may provide a potent technique for restraining decoherence and offer a new platform for quantum resource application.

Complete complementarity relations for quantum correlations in neutrino oscillations with CP violation

We characterize quantum correlations encoded in a three-flavor oscillating neutrino system by taking into account CP violation. By means of the complete complementarity relations (CCR), we study the trade-off of predictability, local coherence and nonlocal correlations by using relevant parameters given by neutrino oscillation experiments. Although the CCR describe very well the contributions associated to bipartite correlations, we explore the possible presence of genuine tripartite correlations, by exploiting polygamy relations. We also provide some observations about the nonlocal advantage of quantum coherence, a mazy quantum correlation characterizing the most valuable, nonlocal, portion of quantum coherence in a multi-partite system.

The nonlocal advantage of quantum coherence and Bell nonlocality under relativistic motion

The nonlocal advantage of quantum coherence and Bell nonlocality under relativistic motion

Investigating and controlling the quantum resources of bipartite-qubit detectors of scalar fields in the process of spacetime expansion

Quantum resources construct new avenues to explore the cosmos. Considering bipartite-qubit detectors subjected to scalar fields in an expanding spacetime, quantum resources (including quantum coherence, quantum discord, Bell-nonlocality, and nonlocal advantage of quantum coherence) of the system are characterized. The influences of various cosmic parameters on these quantum resources are investigated. Besides, we use the filtering operation to propose a strategy that can be used to control these quantum resources. The results reveal that quantum coherence and quantum discord can not disappear at different expansion rapidity, expansion volumes, and particle masses of scalar field. Conversely, one can not capture Bell-nonlocality and nonlocal advantage of quantum coherence at higher expansion rapidity, larger expansion volume, and smaller particle mass. The dissipation of quantum resources can be resisted via the filtering operation. One can use the filtering operation to remarkably strengthen these quantum resources of the system.

Exclusion principle for nonlocal advantage of quantum coherence

Exclusion principle for nonlocal advantage of quantum coherence

Non-locality and entropic uncertainty relations in neutrino oscillations

Using the wave-packet approach to neutrino oscillations, we analyze quantum-memory-assisted entropic uncertainty relations and show that uncertainty and the non-local advantage of quantum coherence are anti-correlated. Furthermore, we explore the hierarchy among three different definitions of NAQC, those based on l_{1}-norm, relative entropy and skew information coherence measures, and we find that the coherence content detected by the l_{1}-norm-based NAQC overcomes the other two. The connection between QMA-EUR and NAQC could provide a better understanding of the physical meaning of the results so far obtained and suggest their extension to quantum field theory.

Characterizing quantum nonlocalities under the Heisenberg XYZ spin model with Dzyaloshinskii–Moriya interaction

In quantum information science, the nontrivial applications of the Heisenberg spin model are to realize quantum communication and quantum computing using the quantum nonlocalities between particles in the spin chain. Here, considering Heisenberg XYZ spin model with Dzyaloshinskii–Moriya (DM) interaction, our attentions are directed to ascertain the nonlocal advantage of quantum coherence (NAQC), and also characterize the Bell nonlocality (BN). As revealed from the results, one can use low temperature to realize situations in which the NAQC and BN are invariant. The NAQC and BN cannot be detected if temperature is high. External temperature strongly influences the two quantum nonlocalities in ferromagnetic systems. The strong coupling parameter brings on the fact that the two quantum nonlocalities are invariant. It is very difficult to capture the NAQC and BN if is weak. Considering , the strong is responsible for freezing quantum nonlocalities, and one cannot witness the NAQC when is low. Moreover, the freezing of quantum nonlocalities can be achieved via enhancing , and the detection of NAQC is difficult if is weak. Of particular note, under the influence of DM interactions, NAQC (BN) cannot (can) be frozen both in antiferromagnetic and ferromagnetic systems. The strong and give rise to the difficulty of capturing the NAQC.

Can NSI affect non-local correlations in neutrino oscillations?

Non-local correlations in entangled systems are usually captured by measures such as Bell’s inequality violation. It was recently shown that in neutrino systems, a measure of non-local advantage of quantum coherence (NAQC) can be considered as a stronger measure of non-local correlations as compared to the Bell’s inequality violation. In this work, we analyze the effects of non standard interaction (NSI) on these measures in the context of two flavour neutrino oscillations for DUNE, MINOS, T2K, KamLAND, JUNO and Daya Bay experimental set-ups. We find that even in the presence of NSI, Bell’s inequality violation occurs in the entire energy range whereas the NAQC violation is observed only in some specific energy range justifying the more elementary feature of NAQC. Further, we find that NSI can enhance the violation of NAQC and Bell’s inequality parameter in the higher energy range of a given experimental set-up; these enhancements being maximal for the KamLAND experiment. However, the possible enhancement in the violation of the Bell’s inequality parameter over the standard model prediction can be up to 11% whereas for NAQC it is 7%. Thus although NAQC is a comparatively stronger witness of nonclassicality, it shows lesser sensitivity to NSI effects in comparison to the Bell’s inequality parameter.

Limits on sequential sharing of nonlocal advantage of quantum coherence

Sequential sharing of nonlocal correlation is inherently related to its application. We address the question as to how many observers can share the nonlocal advantage of quantum coherence (NAQC) in a $(d\times d)$-dimensional state, where $d$ is a prime or a power of a prime. We first analyze the trade-off between disturbance and information gain of the general $d$-dimensional unsharp measurements. Then in a scenario where multiple Alices perform unsharp measurements on one party of the state sequentially and independently and a single Bob measures coherence of the conditional states on the other party, we show that at most one Alice can demonstrate NAQC with Bob. This limit holds even when considering the weak measurements with optimal pointer states. These results may shed light on the interplay between nonlocal correlations and quantum measurements on high-dimensional systems and the hierarchy of different quantum correlations.

Steering quantum nonlocalities of quantum dot system suffering from decoherence

The important applications of quantum dot system are to implement logic operations and achieve universal quantum computing based on different quantum nonlocalities. Here, we characterize the quantum steering, Bell nonlocality, and nonlocal advantage of quantum coherence (NAQC) of quantum dot system suffering nonunital and unital channels. The results reveal that quantum steering, Bell nonlocality, and NAQC can display the traits of dissipation, enhancement, and freezing. One can achieve the detections of quantum steering, Bell nonlocality, and NAQC of quantum dot system in different situations. Among these quantum nonlocalities, NAQC is the most fragile, and it is most easily influenced by different system parameters. Furthermore, considering quantum dot system coupling with amplitude damping channel and phase damping channel, these quantum nonlocalities degenerate with the enlargement of the channel parameters t and Γ. Remarkably, measurement reversal can effectively control and enhance quantum steering, Bell nonlocality, and NAQC of quantum dot system suffering from decoherence, especially in the scenarios of the amplitude damping channel and strong operation strength.

Quantum instrumentality uniquely singles out nonlocal advantage of quantum coherence

Recently, it was shown that quantum steerability is stronger than the bound set by the instrumental causal network. This implies, quantum instrumentality cannot simulate EPR-nonlocal correlations completely. In contrast, here we show that quantum instrumentality can indeed simulate EPR correlations completely and uniquely if viewed from the perspective of NAQC. Implication of our result is that the entire set of EPR-correlations can be explained by the LHS model in the instrumental causal background if viewed from the perspective of NAQC.

Nonlocal advantage of quantum coherence and quantum discord versus internal energy in the Heisenberg chain

Nonlocal advantage of quantum coherence and quantum discord versus internal energy in the Heisenberg chain

Nonlocal advantage of quantum coherence and entanglement of two spins under intrinsic decoherence* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11774406 and 11934018), the National Key Research and Develepment Program of China (Grant Nos. 2016YFA0302104 and 2016YFA0300600), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB28000000), and the Research Program of

We investigate the nonlocal advantage of quantum coherence (NAQC) and entanglement for two spins coupled via the Heisenberg interaction and under the intrinsic decoherence. Solutions of this decoherence model for the initial spin-1/2 and spin-1 maximally entangled states are obtained, based on which we calculate the NAQC and entanglement. In the weak region of magnetic field, the NAQC behaves as a damped oscillation with the time evolves, while the entanglement decays exponentially (behaves as a damped oscillation) for the spin-1/2 (spin-1) case. Moreover, the decay of both the NAQC and entanglement can be suppressed significantly by tuning the magnetic field and anisotropy of the spin interaction to some decoherence-rate-determined optimal values.

Thermal Nonlocal Advantage of Quantum Coherence in the Two-Site, Triangular, and Tetrahedral Lattices with Heisenberg Interactions

Quantum correlations are physical resources for quantum information processing. The nonlocal advantage of quantum coherence (NAQC) is a kind of quantum correlation which is stronger than entanglement. We report here methods for enhancing thermal NAQC in the two-site, triangular, and tetrahedral lattices. It is found that for all the considered cases, the NAQC can be noticeably enhanced by introducing the Dzyaloshinsky-Moriya (DM) interaction to two spins and tune the anisotropy of the spin-spin coupling. Besides, the critical temperature below which the thermal NAQC exists can also be noticeably enhanced by introducing the DM interaction. Hence, our results provide a way to achieve NAQC for quantum tasks based on spin lattices.

Nonlocal advantage of quantum coherence of coupled qubits in thermal and dephasing reservoirs

We investigate the nonlocal advantage of quantum coherence (NAQC) for two qubits coupled via the Heisenberg interaction and embedded in their respective thermal and dephasing reservoirs. Unlike the case of two uncoupled qubits, we showed that in the presence of the Heisenberg interaction, the decay rate of the NAQC can be reduced and the strength of the NAQC can be enhanced for certain initial states. Moreover, the Heisenberg interaction of two spins can induce generation of NAQC from the initial product states, and the generated NAQC approaches asymptotically to its maximum with the increasing anisotropy of the Heisenberg interaction.

Nonlocal advantage of quantum coherence in a dephasing channel with memory* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11675129, 11774406, and 11934018), the National Key R&D Program of China (Grant Nos. 2016YFA0302104 and 2016YFA0300600), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB28000000), and the Research Program of Beijing Academy of

We investigate nonlocal advantage of quantum coherence (NAQC) in a correlated dephasing channel modeled by the multimode bosonic reservoir. We obtain analytically the dephasing and memory factors of this channel for the reservoir having a Lorentzian spectral density, and analyze how they affect the NAQC defined by the l 1 norm and relative entropy. It is shown that the memory effects of this channel on NAQC are state-dependent, and they suppress noticeably the rapid decay of NAQC for the family of input Bell-like states with one excitation. For the given transmission time of each qubit, we also obtain the regions of the dephasing and memory factors during which there is NAQC in the output states.

Enhancing nonlocal advantage of quantum coherence in correlated quantum channels

We explore decay behaviors of the nonlocal advantage of quantum coherence (NAQC) for two qubits traversing the phase flap, bit flip, bit-phase flip, and depolarizing channels. For the input Bell and Bell-diagonal states, we showed analytically that the NAQC of the output states can always be noticeably enhanced due to the correlations between consecutive uses of these quantum channels, and the degree of minimum correlation needed for achieving the NAQC increases with an increase in the decoherence factor. We also explored a colored dephasing channel which enables one to compare the cooperation mechanism of two different origins of memory effects in enhancing the NAQC.

Exploring the nonlocal advantage of quantum coherence and Bell nonlocality in the Heisenberg XYZ chain

The non-local advantage of quantum coherence (NAQC) is regarded as a quantum correlation, which can be reflected by the violation of a set of inequalities based on various coherence measures. In this work, we explore the NAQC and Bell nonlocality (BN) in a two-qubit Heisenberg XYZ model. The results show that one can capture the BN in the case of both anti-ferromagnetism and ferromagnetism. By contrast, the NAQC cannot be achieved in the ferromagnetism case if the magnetic field is strong. Increases of inhomogeneity and temperature give rise to reductions of the NAQC and BN, and the achievement of the NAQC at high inhomogeneity or temperatures becomes very difficult. Also, the NAQC and BN strengthen with an increase of the mean coupling coefficient. A strong mean coupling coefficient leads to the freezing of the NAQC and BN when the inhomogeneity is low. The enhancement of the magnetic field can result in the fact that the NAQC and BN experience four processes, including reduction, sudden death, revival, and reduction. Additionally, the BN is easier to capture than the NAQC. Furthermore, we focus our attention on controlling the NAQC and BN via a local filtering operation. The results demonstrate that the operation can effectively strengthen the NAQC and BN, and can also help us to control the NAQC and BN in the Heisenberg XYZ chain.

Restrain the losses of the entanglement and the non-local advantage of quantum coherence for accelerated quantum systems

We examined the possibility of recovering the losses of entanglement and the non-local advantage by using the local symmetric operations. The improvement efficiency may be increased by applying the symmetric operations on both qubits. The recovering process of both phenomenon is exhibited clearly when only one qubit is accelerated and the symmetric operations is applied on both qubits. It is shown that, for large acceleration, the non-local coherent advantage may be re-birthed by using these symmetric operations.

Quantification of quantumness in neutrino oscillations

Neutrino oscillation is an important physical phenomenon in elementary particle physics, and its nonclassical features can be revealed by the Leggett–Garg inequality. It shows that its quantum coherence can be sustained over astrophysical length scales. In this work, we investigate the measure of quantumness in experimentally observed neutrino oscillations via the nonlocal advantage of quantum coherence (NAQC), quantum steering, and Bell nonlocality. From various neutrino sources, ensembles of reactor and accelerator neutrinos are analyzed at distinct energies, such as Daya Bay (0.5 km and 1.6 km) and MINOS (735 km) collaborations. The NAQC of two-flavor neutrino oscillation is characterized experimentally compared to the theoretical prediction. It exhibits non-monotonously evolutive phenomenon with the increase of energy. Furthermore, it is found that the NAQC is a stronger quantum correlation than quantum steering and Bell nonlocality even in the order of km. Hence, for an arbitrary bipartite neutrino-flavor state with achieving a NAQC, it must be also a steerable and Bell nonlocal state. The results might offer an insight into the neutrino oscillation for the further applications on quantum information processing.