纠缠是依赖于时间的吗?
Is entanglement observer-dependent?
摘要:
研究了量子纠缠的性质,指出了观察者的作用。
英文摘要:
The properties of quantum entanglement are examined and the role of the observer is pointed out.
机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。
Is entanglement observer-dependent?
Italo Vecchi
研究了量子纠缠的性质,指出了观察者的作用。
The properties of quantum entanglement are examined and the role of the observer is pointed out.
机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。
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Tripartite entanglement of fermionic system in accelerated frames
研究了非惯性系中费米子系统在一个或两个观测者加速时,通过线性压缩判据产生的三重纠缠动力学。在单观测者加速的情况下,纠缠测量对于不同子系统的部分重新排列不是不变的,而对于两个观测者加速的情况,纠缠测量是不变的。结果表明,框架的加速度不产生纠缠在任何二分子系统。与二体态不同,即使在无限加速的极限下,真正的三体纠缠在单观察者加速和两观察者加速的情况下也不会完全消失。当两个观察者加速时,三重纠缠的退化比一个观察者加速时快。结果表明,在非惯性系中,三体纠缠是比二体纠缠更好的量子信息处理资源。
Recycled detection of genuine multiparty entanglement of unlimitedly stretched array of parties and arbitrarily long series of sequential observers
研究空间分离观测者共享多体纠缠态的场景,提出改进的纠缠见证算子,证明任意数量观测者可循环检测任意数量粒子的真正多体纠缠,并扩展至广义GHZ态与混合态。
Violation of a Bell inequality certifies that the underlying state must be entangled in a device-independent way, although there may exist some entangled states which do not violate such an inequality. On the other hand, for every entangled state, it is possible to find a hermitian operator called entanglement witness that can detect entanglement through some local measurements in a device-dependent method. The methods are significantly fragile to lossy detectors. To avoid such difficulties, measurement-device-independent entanglement witness based on a semi-quantum nonlocal game was proposed …
Concentrating Partial Entanglement by Local Operations
如果两个分离的观察者被提供纠缠,以$n$粒子对的形式,它们处于完全相同的部分纠缠纯态,每对中的一个成员被给予每个观察者;他们可以通过每个观察者的局部作用,将这种纠缠集中到更少数量的最大纠缠粒子对中,例如爱因斯坦-波多尔斯基-罗森单线态,类似地在两个观察者之间共享。浓度过程渐近地保存{ \em纠缠熵}-由任一观察者看到的偏密度矩阵的冯诺伊曼熵-与单态的产量接近,对于大$n$,初始部分纠缠纯态的基2纠缠熵。相反,两个系统的任何纯纠缠态或混合纠缠态都可以由两个经典通信的分离观察者产生,并将单线态作为其唯一的纠缠源。
We investigate the scenario where an observer, Alice, shares a two-qubit state with an arbitrary number of observers, Bobs, via sequentially and independently recycling the qubit in possession of the first Bob. It is known that there exist entangled states which can be used to have an arbitrarily long sequence of Bobs who can violate the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality with the single Alice. We show that there exist entangled states that do not violate the Bell inequality and whose entanglement can be detected by an arbitrary number of Bobs by suitably choosing the entangleme…
We investigate the witnessing of two-qubit entangled states by sequential and independent pairs of observers, with both observers of each pair acting independently on their part of the shared state from spatially separated laboratories, and subsequently passing their qubits to the next pair in the sequence. It has previously been conjectured that not more than one pair of observers can detect Clauser-Horne-Shimony-Holt "Bell-nonlocal" correlations in a similar set-up. This is intriguing since it is possible to have an arbitrarily long sequence of Bell-nonlocal correlations when only a single o…
Decoherence and multipartite entanglement of non-inertial observers
研究了非惯性系中退相干对多体纠缠的影响。GHZ态被认为是伙伴之间共享的,其中一个伙伴在惯性系中,而另外两个伙伴在加速系中。用单缠结和π缠结来量化相位阻尼和相位翻转通道对多体系统纠缠度的影响。结果表明,对于相位阻尼通道,在无限加速极限下,当p>0.5时,纠缠突然死亡(ESD)。另一方面,在相位翻转通道的情况下,ESD行为发生在50%的退相干附近。在相位翻转通道中,纠缠态的突然诞生(ESB)现象确实存在。此外,环境对多体纠缠的影响要比非惯性系加速度的影响大得多。
Observer dependent entanglement
理解量子纠缠的纠缠依赖性是相对论量子信息研究的核心问题。在本文中,我们将审查的相对论性纠缠在平坦和弯曲的时空和讨论最近的工作表明,运动和重力有可观察到的局域系统之间的纠缠的关键结果。
Due to the difficulties present in experimentally preparing genuine tripartite entanglement, it is important to explore the possibility of multiple usage of a single genuine entangled state. In the present paper, we present one such possibility by considering a scenario consisting of three spin-$\frac{1}{2}$ particles shared between Alice, Bob and multiple Charlies. Alice performs measurements on the first particle, Bob performs measurements on the second particle and multiple Charlies perform measurements on the third particle sequentially and independently. In this scenario, we investigate w…
Spin and occupation number entanglement of Dirac fields for non-inertial observers
我们考虑了狄拉克场的自旋自由度,研究了Unruh效应对纠缠的影响。我们分析了自旋Bell态在这种情况下,获得它们的纠缠依赖于其中一个合作伙伴的加速度。然后,我们考虑简单的类似的占据数纠缠态|00>+|11>,但自旋量子数为|11>示出了,尽管它们明显相似,但无自旋情况总是量子位X量子位,对于自旋情况,加速产生量子位X量子位状态。我们还介绍了一个程序,始终删除自旋信息从我们的设置保留占领号码。我们展示了占据数的最大纠缠态是如何从我们的设置中出现的,我们还分析了它的纠缠依赖于加速度,得到了比无自旋情况下更大的纠缠退化。
Is bound entanglement Lorentz invariant?
本文发现束缚纠缠并非洛伦兹不变:相对论观测者可能将同一自旋态分类为可分、束缚或自由纠缠,解释了纠缠度量难以普适的原因。
It was recently shown that, in general, the von Neumann spin entropy of fermionic particles is not invariant under Lorentz boosts. We show that an analogous result can be recovered (at the lowest order of $v^2 /c^2$) using plain nonrelativistic quantum mechanics provided one uses that energy weighs: $E=m c^2$. This should (i) help to moderate the skepticism on the observer-dependence of the spin entropy of fermionic particles, (ii) emphasize the soft relativistic nature of this result, and (iii) show that this is a particular case of a more general class of systems, since our calculation only …
Local entanglement transfer to multiple pairs of spatially separated observers
研究在有限预共享纠缠下,通过局部联合酉操作将Alice-Bob对的纠缠连续转移到多对空间分离观测者的方法,并分析了转移纠缠量与最大对数。
Sequentially witnessing entanglement by independent observer pairs
本文研究多对独立观察者依次见证纠缠的测量策略,提出一种新策略,使任意 Alice 与 Bob 配对均可在 Bell 态或特定混合纠缠态下见证纠缠。
Experimental detection of entanglement certainly disturbs the underlying shared state. It is possible that the entanglement content of the system is lost in the process of its detection. This observation has led to the study of sequential detection properties of various quantum correlations. Here, we investigate the sequential detection of genuinely multipartite entanglement of quantum systems composed of an arbitrary number of qubits. In order to detect genuine multipartite entanglement sequentially, observers can recycle any fixed subset of all the qubits, thus leading to a hierarchy of scen…
Quantum Statistics and Entanglement Problems
量子测量理论的解释一直受到两个问题的困扰,一个是关于观察者意识的作用,另一个是由量子态叠加引起的纠缠现象。我们在这里强调量子统计在正确描述纠缠问题中的显着作用,并讨论了与当前讨论纠缠,散肩量子世界中智能观察者所产生的问题的关系。
Tripartite Entanglements in Non-inertial Frames
讨论了由一个惯性观测者和两个匀加速观测者观测的非相互作用量子场的模构成的GHZ或W三重态的Unruh效应引起的纠缠退化.对于费米子态,即使无限加速度下的Unruh效应也不能完全消除纠缠。然而,对于玻色子态,情况不同,纠缠渐近消失。此外,还研究了两体子系统的纠缠。虽然对于GHZ态,所有的二部子系统都是相同的解纠缠,但对于W态,二部子系统有些纠缠,尽管如此,这种纠缠可以通过适当加速的观察者来消除。有趣的是,对数负性作为确定系统的一部分相对于其他两部分的纠缠度的度量,对于不同的部分通常是不一样的。这意味着我们遇到了三方系统,其中每个部分与其他两个部分的纠缠不同。
Decoherence is an unavoidable phenomenon that results from the interaction of the system with its surroundings. The study of decoherence due to the relativistic effects has the fundamental importance. The Unruh effect is observed by the relativistically accelerator observer. The unruh effect acts as a quantum channel and we call it the Unruh Channel. The Unruh channel can be characterize by providing its Kraus representation. We consider the bipartite scheme in which the quantum information is shared between an inertial observer (Alice) and an accelerated observer (Rob) in the case of Dirac fi…
Degradation of entanglement in moving frames
研究了两体纠缠态在运动观察者眼中的可分辨性。研究发现,对于一个状态参数$α$和它的"归一化伙伴" $\sqrt{1-α^2}$,相同的初始纠缠在移动的观测者看来会退化。结果表明,在超相对论极限下,对于任何$α$,态都不具有可纠缠性。
Witnessing entanglement sequentially: Maximally entangled states are not special
我们调查共享的二分纠缠的情况下,纠缠对的一半是拥有和投影测量的一个观察者,称为爱丽丝,而另一半进行测量顺序,独立,和unsharply,由多个观察者,称为鲍勃。我们发现,在这种纠缠分布的情况下,观察者的数量是有限制的。特别是,对于两个量子比特的最大纠缠初始共享态,不超过12个鲍勃可以检测到与单个爱丽丝的纠缠,对于鲍勃测量的任意-可能不相等-锐度参数。此外,鲍勃的数量保持不变的一个有限范围内的近最大纯初始纠缠,也发生在相同的锐度参数的情况下,在鲍勃的功能。此外,我们表明,对于非最大纠缠共享纯态,Bobs的数量减少与初始纠缠的量,提供了一个粗粒度的,但可操作的纠缠措施。
Entanglement verification and steering when Alice and Bob cannot be trusted
存在各种协议,通过这些协议,裁判可以确信两个观察者共享纠缠资源。这种协议通常指定了裁判和每个观察者之间允许的通信类型和所需的信任程度。在这里,它表明,裁判员的任何程度的信任的观察员的需要,可以完全删除通过裁判适当地使用经典和量子通信信道。特别是,贝尔非定域性,EPR转向,纠缠,分别需要两个经典的通道,一个经典和一个量子通道,和两个量子信道的无信任验证。这些通道对应于裁判的量子随机性的适当输入,这防止了观察者使用共享的经典随机性来模仿纠缠。我们的结果推广了Buscemi [Phys. Rev. Lett. 108,200401(2012)],并就这项工作的业务意义提供了一个视角。它们还提供了一种可能性,可以用更简单的实验来证明量子非定域性检验的基本思想。
Entanglement dynamics of non-inertial observers in a correlated environment
研究了非惯性系中退相干和关联噪声对Dirac场X型态纠缠的影响。两个量子比特的X状态被认为是在伙伴之间共享的,其中Alice在惯性系中,Rob在加速系中。利用纠缠度来量化时间相关振幅阻尼、去极化和比特翻转通道对X态纠缠度的影响。可以看出,振幅阻尼和比特翻转信道严重影响系统的纠缠相比,去极化信道。当μ>0.75时,对于任何初始态,都可以避免纠缠猝死(ESD).对于退相干参数p和罗布加速度r的整个范围,在存在相关噪声的情况下,对于去极化通道没有看到ESD行为。环境的影响比被加速伙伴的加速度的影响大得多。进一步研究了关联噪声对Unruh效应引起的纠缠损失的补偿作用。
Quantum Teleportation with an Accelerated Observer and Black Hole Information
对在环境连续影响下,利用相对论运动观测者携带的振子变量实现量子纠缠和量子隐形传态协议进行了非微扰分析。研究了静态和加速观测者之间量子纠缠的全时演化。环境起着双重作用。虽然它在初始态可分离的情况下也会在观察者之间产生二分和三分纠缠,但它通过退相干抑制了纠缠。受黑洞信息问题的启发,我们考虑了静态观测者和加速观测者之间的量子隐形传态。观察者的加速度抑制了隐形传态的保真度。在隐形传态过程中,部分量子信息会以二体和三体纠缠的形式逃逸出视界。提供了信息损失的显式计算。除了由于与环境的相互作用而造成的损失之外,还有一种内在的损失源于测量过程。我们讨论的影响,我们的结果对黑洞的情况。
Entanglement dynamics of light's orbital angular momentum under a Lorentz boost
本研究探讨了在洛伦兹变换下光子轨道角动量纠缠的动力学变化,发现其纠缠特性依赖于观察者并提出关于纠缠态时空不变性的新问题。
Using the single-mode approximation, we first calculate entanglement measures such as negativity ($1-3$ and $1-1$ tangles) and von Neumann entropy for a tetrapartite W-Class system in noninertial frame and then analyze the whole entanglement measures, the residual $π_{4}$ and geometric $Π_{4}$ average of tangles. Notice that the difference between $π_{4}$ and $Π_{4}$ is very small or disappears with the increasing accelerated observers. The entanglement properties are compared among the different cases from one accelerated observer to four accelerated observers. The results show that there sti…
In an entanglement swapping scenario, if two sources sharing entangled states between three parties are independent, local correlations lead to a different kind of inequalities than the standard Bell inequalities, known as network local models. A highly demanding task is to find out a way to involve many players nontrivially in a quantum network since measurements, in general, disturb the system. To this end, we consider here a novel way of sharing network nonlocality when two observers initially share close to a maximally entangled states. We report that by employing unsharp measurements perf…
Quantum discord between relatively accelerated observers
我们计算了标量场的两个自由模之间的量子不和谐,这两个自由模开始于一个最大纠缠态,然后经历一个相对恒定的加速度。在一个制度中,没有可解释的纠缠由于Unruh效应,我们表明,有一个有限量的量子不和谐,这是一个纯粹的量子相关性的状态,超过量子纠缠。即使在无限加速的观察者检测模式之一的限制,我们提供了一个非零量的纯量子相关性,这可能被利用来获得非平凡的量子优势的证据。
Speeding up Entanglement Degradation
两个自由玻色子模式之间的纠缠可以通过不同的观察者检测每个模式,然后观察它们的测量之间的相关性来确定。我们表明,这种纠缠退化作为时间的函数,如果一个观察者开始在惯性运动的状态,但在均匀加速的状态,而另一个保持惯性结束。在晚些时候,我们恢复以前建立的结果观察员在相对均匀加速。
Relativistic-invariant quantum entanglement between the spins of moving bodies
一对粒子的自旋之间的纠缠可能会改变,因为当被移动的观察者观察时,自旋和动量变得混合[R.M. Gingrich和C. Adami,Phys. Rev. 89,270402(2002)]。在本文中,它表明,如果动量是适当的纠缠,贝尔态的自旋之间的纠缠可以保持最大时,由任何移动的观察者。此外,我们还提出了一种相对论不变的量子通信协议,使非相对论量子信息理论可以不变地应用于相对论情形。
Entanglement and nonlocality of a single relativistic particle
最近的研究表明,纠缠和非定域性的概念必须认真对待,即使在系统中只由一个粒子。然而,这些处理都是非相对论的,如果单粒子纠缠是基本的,它也应该坚持相对论的描述。在这里,我们考虑一个自旋为1/2的粒子在两个不同的速度叠加,观察者在不同的相对论增强惯性系。我们证明了纠缠在光速下仍然存在,并且增强的观察者会看到单粒子违反贝尔不等式。我们还讨论了如何量子门可以实现这种方式和量子信息处理的可能影响。
Alice falls into a black hole: Entanglement in non-inertial frames
两个观察者通过各自检测其中一个模式并观察它们测量值之间的相关性来确定两个自由玻色子模式之间的纠缠。我们证明了,如果观察者相对加速,在惯性系中最大纠缠的状态变得不那么纠缠。这一现象是Unruh效应的结果,表明在非惯性系中纠缠是一个依赖于粒子数的量。在高加速度极限下,我们的结果可以应用于非加速观测者落入黑洞而加速观测者几乎无法逃脱的情形。如果观察者以无穷大的加速度逃逸,状态的可解纠缠就消失了。
In this thesis we focus on the influence of uniform acceleration on quantum states and their properties, as well as on quantum entanglement contained in the vacuum. First, we analyze a quantum clock measuring time in terms of the decay of an unstable particle. We compare the rate of ticking of a stationary clock to the one of a uniformly accelerating clock. We discover that there exists a deviation from what the discrepancy between those rates is predicted to be by special relativity. In a further part of this thesis we focus on the family of two-mode Gaussian states of two localized modes of …
Entanglement of Dirac fields has been studied and it is known to decrease with increasing acceleration when a quantum state is shared between users in non-inertial frames. A new form of an entangled vacuum state observed by the accelerated observer is postulated in which it is assumed that entanglement is present between the modes of the quantum field with sharp and opposite momenta defined in two causally disconnected regions of space-time. We find that this assumption does not affect the entanglement of the system.
Continuous variable entanglement sharing in non-inertial frames
从匀加速观测者的角度研究了自由标量场模间纠缠的分布。从惯性的角度考虑双模压缩态的光场,并分析研究了在一个或两个观测者均为匀加速的情况下,由于Unruh效应而引起的纠缠退化.我们发现,对于两个观察员进行有限的加速,纠缠消失之间的最低频率模式。从非惯性的角度,纠缠的丢失被精确地解释为惯性纠缠重新分配为可达和不可达模式之间的多体量子关联。我们表明,经典的相关性也失去了从两个加速观察员的角度来看,但保守的,如果观察员之一仍然惯性。
Asymmetric quantum telecloning of d-level systems and broadcasting of entanglement to different locations using the "many-to-many" communication protocol
我们提出了一种广义的量子隐形传态:一个d能级系统的信息从N个空间分离的量子点到位于不同位置的M>N个接收器的所谓多对多量子通信。我们将非对称远距克隆的概念从量子比特扩展到d维系统。我们研究了利用局域1->2最优普适非对称泡利机传播纠缠,并证明了当采用对称泡利机时,两个最终纠缠态的纠缠度达到最大.利用非局部最优的通用非对称克隆机研究了纠缠的克隆,证明了对称克隆机可以最优地复制纠缠。采用“多对多”隐形传态方案,将两个观测者之间的纠缠分配给两对空间分离的观测者。
Purification of Noisy Entanglement and Faithful Teleportation via Noisy Channels
两个分离的观察者,通过对一个不太纯的纠缠态({ \em例如})进行局域操作,得到了两个分离的观察者的纠缠态。通过噪声通道共享的单态),可以制备更少数量的任意高纯度的纠缠对({ \em,例如}近乎完美的单线态)。然后,这些可以被用来忠实地将未知的量子态从一个观察者传送到另一个观察者,从而实现从一个观察者到另一个观察者的忠实传送,从而实现量子信息通过噪声信道的忠实传输。我们给出了从混合态$M$可获得的纯单态($\ket{Ψ^-}$)的产额$D(M)$的上、下界,证明了如果$\bra{Ψ^-}M\ket{Ψ^-}>\half$满足$D(M)>0$.
From observer-dependent facts to frame-dependent measurement records in Wigner friend scenarios
该研究在相对论背景下提出模型,表明维格纳友人场景中支持观察者依赖事实的假设可导致测量记录依赖于惯性参考系,且不同参考系观察者的记录并非洛伦兹变换。
The Minkowski vacuum $|0\rangle_M$, which for an inertial observer is devoid of particles, is treated as a thermal bath by Rindler observers living in a single Rindler wedge, as a result of the discrepancy in the definition of positive frequency between the two classes of observers and a strong entanglement between degrees of freedom in the left and right Rindler wedges. We revisit, in the context of a free scalar Klein-Gordon field, the problem of quantification of the correlations between an inertial observer Alice and left/right Rindler observes Rob/AntiRob. We emphasize the analysis of inf…
Two-particle entanglement as a property of three-particle entangled states
在最近的一篇文章[Phys. Rev. A 54,1793(1996)]中,Krenn和Zeilinger研究了通过选择两个观察者1和2的自旋测量结果与第三个观察者的相应测量结果得到的数据子系综的条件两粒子关联。在本文中,我们明确地写出了所需的条件,以便观察员1和2的选择结果违反贝尔不等式的一般测量方向。它表明,有无限多套方向给出最大程度的违反。进一步,我们将作者的分析推广到三正交态类|Psi> = c_1| z_1>| z_2>| z_3> + c_2|-z_1>|-z_2>|-z_3>。结果发现,一个最大的违反贝尔不等式发生提供相应的三粒子状态产生一个直接的(“全部或没有”)非定域性矛盾。
Observer-Dependent Entropy and Diagonal Rényi Invariants in Quantum Reference Frames
本文研究了量子参考框架中观察者依赖的熵问题,提出了一种对角Rényi熵家族,揭示了多体系统中相干性与纠缠性的贸易关系,并探讨了理想与非理想参考框架下熵的约束。
We have studied entanglement between two Dirac modes respectively observed by two independently accelerated observers. Due to Unruh effect, the entanglement degrades, but residual nonzero entanglement remains even when the accelerations of both observers are infinite. We have also investigated quantum teleportation using entangled Dirac modes, and calculated the fidelities in various cases. In general, the fidelity depends on the single-qubit state $γ|0\rangle +δ|1\rangle$ to be teleported, as well as which Bell state to use. In the limit that both accelerations are infinite, the average fidel…
We generalize $1+1$-dimensional formalism derived by Ahmadi et. al. [Phys. Rev. D \textbf{93}, 124031] to investigate an effect of relativistic acceleration on localized two-mode Gaussian quantum states in $3+1$-dimensional spacetime. The following framework is then used to analyze entanglement of the Minkowski vacuum as witnessed by two accelerating observers that move either collinearly or noncollinearly.
Effect of the readout efficiency of quantum measurement on the system entanglement
本文研究低效监测下一维量子随机游走中测量强度和读出效率对系统纠缠的影响,发现高效读出能显著提升纠缠,对量子计算和测量诱导相变研究具有重要意义。
Entanglement as an Observer-Dependent Concept: An Application to Quantum Phase Transitions
本文解决了以下主要问题:我们有一个理论上的理解纠缠适用于各种各样的物理设置?很明显,不仅可互换性的假设,而且少子系统的情况下,太窄,包括所有可能的物理设置。特别是,当人们试图将传统的纠缠概念应用于物质物理学时,超越传统的基于子系统的框架的必要性变得明显,因为量子多体系统的组成部分是不可区分的粒子。我们将在这里讨论广义纠缠的概念,它可以应用于任何算子语言(费米子,玻色子,自旋等)。用来描述一个物理系统,它包括迄今为止以统一方式介绍的传统纠缠设置。这是通过注意到纠缠是一个依赖于时间的概念来实现的,其属性由一组可观察量的期望来确定,而不参考优选的子系统分解,即,这取决于物理相关的观点。这个观点反过来又取决于不同的可观测量之间的关系,这些可观测量决定了我们控制感兴趣的系统的能力。事实上,纠缠存在的程度取决于用于测量系统和描述其状态的可观测量。这代表了一个最显著的优点,我们将讨论的凝聚态应用将突出这一点。
Entanglement Structures in Quantum Field Theories II: Distortions of Vacuum Correlations Through the Lens of Local Observers
本文研究局部探测器观察量子场时纠缠受限问题,提出通过投影测量和经典通信识别纯态的协议,发现类空纠缠与局部可检测纠缠的差异随分离指数增长。
Detection of entanglement in asymmetric quantum networks and multipartite quantum steering
量子通信的未来依赖于由共享多体量子态的观察者组成的量子网络。多方纠缠的认证对于这些网络的有用性至关重要。在许多实际情况下,很自然地假设一些观察者比其他观察者更可信,因为他们对他们的测量设备有更多的了解。在这里,我们提出了一个通用的方法来证明各种多体纠缠在这种不对称的情况下,并在光学实验中证明它。我们的结果,这可以被看作是一个真正的多体量子转向的定义,给出了一种方法来检测之间的标准纠缠和完全设备无关的情况下的情况下的纠缠,并在量子网络中的半设备无关的加密应用提供了基础。
Demonstrations of quantum entanglement which confirm the violation of Bell's inequality indicate that under certain conditions action at a distance is possible. This consequence seems to contradict the relativistic principle of causality, which asserts that an effect never precedes its cause, in any reference frame. By analyzing a numerical example of Bell's experiment with entangled pairs of photons, we show how observers in two inertial reference frames can disagree about the causality relation between two events. One observer claims that event 1 is the cause of event 2, while the other clai…
How best one can recycle a given quantum resource, mitigating the various difficulties involved in its preparation and preservation, is of considerable importance for ensuring efficient applications in quantum technology. Here we demonstrate quantitatively the resource theoretic advantage of reusing a single copy of a two-qubit entangled state towards information processing. To this end, we consider a scenario of sequential entanglement detection of a given two-qubit state by multiple independent observers on each of the two spatially separated wings. In particular, we consider equal numbers o…
Relativistic entanglement and Bell's inequality
本文研究了运动观测者看到的纠缠Bell态的洛伦兹变换。4次联合测量的Bell观测值给出了一个普适值$<\hat{a}\otimes\vec{b}>+<\hat{a}\otimes\vec{b}'>+\lang le\hat{a}'\otimes\vec{b}> -<\hat{a}'\otimes\vec{b}'>=\frac{2}{\sqrt{2-β^2}}(1+\sqrt{1-\be ta^2})$,其中$\hat{a}, \hat{b}$是由Pauli-Lubanski赝矢量和$β=\frac{v}{c}$导出的相对论自旋观测值。我们发现,贝尔不等式的破坏程度随着观察者速度的增加而减小,并且贝尔不等式在超相对论极限下满足,其中加速速度达到光速。
Reply to Ryff's Comment on "Experimental Nonlocality Proof of Quantum Teleportation and Entanglement Swapping"
Ryff的评论提出了量子态的意义问题。我们认为,量子态只是一个给定的观察者可用的信息的代表。那么赖夫对我们的一个实验的解释和我们最初的实验都是可以接受的。
Entanglement Degradation in Causal Diamonds
本文研究因果钻石视界对二体纠缠的影响,证明惯性观测者 Alice 与寿命受限的钻石观测者 Dave 共享的最大纠缠态会因因果视界而发生退化。
Spin-momentum correlation in relativistic single particle quantum states
本文研究了单粒子量子态中的自旋动量关联,该量子态在洛伦兹变换下用混合态描述。为了方便起见,我们只使用两个垂直于洛伦兹助推方向的动量本征态(p1和p2),而不是使用动量叠加。因此,在二维动量子空间中,我们证明了运动标架中自旋-动量的纠缠依赖于它们之间的夹角。因此,当自旋和动量垂直时,纠缠度量在惯性系中不是依赖于自旋的量。同样,我们计算了纠缠度(通过使用并发),并表明纠缠度随着观察者速度的增加而减小。最后,我们论证了Wigner旋转是由洛伦兹变换引起的,可以作为控制算符来实现。
Relativistic entanglement of two massive particles
我们把两个大质量自旋- $\tfrac{1}{2}$粒子系统的自旋和动量自由度描述为一个4量子比特系统。然后,我们显式地显示了如何纠缠的变化之间的不同分区的量子比特,当考虑不同的惯性观测器。虽然两个粒子的纠缠对应于一个分区到爱丽丝和鲍勃的子系统是,正如文献中经常指出的,洛伦兹助推下不变,纠缠相对于其他分区的希尔伯特空间,另一方面,不是。它当然取决于所选择的惯性系和所考虑的初始状态。纠缠的变化出现了,因为洛伦兹对粒子动量的提升导致了自旋的维格纳旋转,在某些情况下,自旋与动量态纠缠在一起。我们系统地研究了不同类型的初始自旋状态和不同的分区的4量子比特空间的情况。此外,我们研究了贝尔不等式的行为,不同的观察者和演示如何最大可能程度的违反,使用保利-鲁班斯基自旋可观察,可以恢复任何惯性观察者。
Population bound effects on bosonic correlations in non-inertial frames
我们分析的影响,边界的玻色子场模式的占领数的所有不同的时空区域之间的相关性的设置,在该设置中,我们有一个时空的地平线以及惯性观察员。我们证明了A(惯性观察者)和R(匀加速观察者)之间的纠缠依赖于束缚N,与费米子的情况相反。去相干是否随N增加而增加取决于加速度a的值。关于二分区A-antiR(爱丽丝与观察员在Rindler的区域IV),我们表明,没有纠缠创建的N和a的值。此外,AR纠缠对于有限N和无限N都很快丢失。我们将详细研究玻色子和费米子的互信息守恒定律。通过与N有限性相关的边界效应,我们将证明,对于玻色子,这一定律源于经典关联,而对于费米子,它具有量子起源。最后,我们将介绍在R-antiR双划分纠缠的强N依赖性和比较费米子的情况下,他们的有限N玻色子类似物。我们还将展示这种纠缠对统计数据的反直觉依赖,因为玻色子的纠缠比费米子的纠缠多。
Observers following special classes of finite-lifetime trajectories have been shown to experience an effective temperature, a generalisation of the Unruh temperature for uniformly accelerated observers. We consider a mirror following such a trajectory - and is hence localised to a strictly bounded causal diamond - that perfectly reflects incoming field modes. We find that inertial observers in the Minkowski vacuum detect particles along the half null-rays at the beginning and end of the mirror's lifetime. These particle distributions exhibit multi-partite entanglement, which reveals novel stru…
Hidden entanglement at the Planck scale: loss of unitarity and the information paradox
我们讨论了如何放松量子场的局部性要求,可以配备希尔伯特空间的理论,在其多粒子部门的更丰富的结构。一个物理后果是出现了一个“普朗克”模式纠缠,无法探测普朗克尺度的观察者是看不见的。对于同一观察者来说,某些统一处理过程将显得非统一处理。我们展示了如何纠缠转移到额外的自由度可以提供一个潜在的出路的黑洞信息悖论。
Implementation of classical communication in a quantum world
由有限观测者进行的量子系统的观测,随后使用经典数据结构来传达他们的结果,可以被描述为“局部操作,经典通信”(LOCC)观测。研究了用最小量子力学描述的哈密顿动力学实现LOCC观测的问题。它表明,LOCC观测不能单独使用消相干的考虑来描述,而是需要\textit{a priori}规定的一个积极的运营商价值的措施(POVM)有关的通信观察员同意。它还表明,从系统到观察者的经典信息的传输可以描述在系统观察者纠缠,提高的可能性,实现适当的POVM的设备可以揭示纠缠的系统观察者状态,实现LOCC观测。
Sudden death of effective entanglement
纠缠的突然消亡是一个众所周知的效应,由有限体积的可分离态。我们研究的情况下,观察者有一个有限的测量能力和分析的有效纠缠,即纠缠最小化的输出数据。我们表明,在由单电子晶体管监控的两个量子点的明确定义的系统中,当真实的物理纠缠仍然存在时,可以观察到有效纠缠的突然死亡。对于某些测量设置,甚至对于物理纠缠的突然死亡根本不可能的初始状态也会发生这种情况。分析的原理可以应用于其他类似的场景,例如从量子过程层析成像产生的参数的估计。
Entanglement and discord: accelerated observations of local and global modes
我们从Alice(惯性)和Rob(加速)两个观察者的角度研究了双模压缩态中纠缠和量子不和谐的数量。我们发现,使用本地化的模式产生定性不同的相关特性,大的加速度比Unruh模式。具体地说,纠缠经历了一个突然死亡的函数的加速度和不和谐渐近为零的极限无限加速。我们的结论是,以前的Unruh模式分析不确定的加速度依赖的纠缠和不和谐退化的一个给定的量子态。
Einstein-Podolsky-Rosen (EPR) steering, a category of quantum nonlocal correlations describing the ability of one observer to influence another party's state via local measurements, is different from both entanglement and Bell nonlocality by possessing an asymmetric property. For multipartite EPR steering, the monogamous situation, where two observers cannot simultaneously steer the state of the third party, has been investigated rigorously both in theory and experiment. In contrast to the monogamous situation, the shareability of EPR steering in reduced subsystems allows the state of one part…
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