اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدTesting Hardy nonlocality proof with genuine energy-time entanglement
64
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We show two experimental realizations of Hardy ladder test of quantum nonlocality using energy-time correlated photons, following the scheme proposed by A. Cabello emph{et al.} [Phys. Rev. Lett. textbf{102}, 040401 (2009)]. Unlike, previous energy-time Bell experiments, these tests require precise tailored nonmaximally entangled states. One of them is equivalent to the two-setting two-outcome Bell test requiring a minimum detection efficiency. The reported experiments are still affected by the locality and detection loopholes, but are free of the post-selection loophole of previous energy-time and time-bin Bell tests.
قيم البحث
اقرأ أيضاً
We explore the relationship between randomness and nonlocality based on arguments which demonstrate nonlocality without requiring Bell-type inequalities, such as using Hardy relations and its variant like Cabello-Liang (CL) relations. We first clarif
y the way these relations enable certification of Genuine Randomness (GR) based on the No-signalling principle. Subsequently, corresponding to a given amount of nonlocality, using the relevant quantifier of GR, we demonstrate the following results: (a) We show that in the 2-2-2 scenario, it is possible to achieve close to the theoretical maximum value of 2 bits amount of GR using CL relations. Importantly, this maximum value is achieved using pure non-maximally entangled states for the measurement settings entailing small amount of nonlocality. Thus, this illustrates quantitative incommensurability between maximum achievable certified randomness, nonlocality and entanglement in the same testable context. (b) We also obtain the device-independent guaranteed amount of GR based on Hardy and CL relations, taking into account the effect of varying preparation procedure which is necessary for ensuring the desired security in this case against adversarial guessing attack. This result is compared with that obtained earlier for the Bell-CHSH case. We find that the monotonicity between such guaranteed randomness and nonlocality persists for the Hardy/CL like for Bell-CHSH inequality, thereby showing commensurability between guaranteed randomness and nonlocality, in contrast to the case of maximum achievable randomness. The results of this combined study of maximum achievable as well as guaranteed amounts of GR, obtained for both fixed and varying preparation procedures, demonstrate that the nature of quantitative relationship between randomness and nonlocality is crucially dependent on which aspect (guaranteed/maximum amount) of GR is considered.
The network structure offers in principle the possibility for novel forms of quantum nonlocal correlations, that are proper to networks and cannot be traced back to standard quantum Bell nonlocality. Here we define a notion of genuine network quantum
nonlocality. Our approach is operational and views standard quantum nonlocality as a resource for producing correlations in networks. We show several examples of correlations that are genuine network nonlocal, considering the so-called bilocality network of entanglement swapping. In particular, we present an example of quantum self-testing which relies on the network structure; the considered correlations are non-bilocal, but are local according to the usual definition of Bell locality.
Any practical realization of entanglement-based quantum communication must be intrinsically secure and able to span long distances avoiding the need of a straight line between the communicating parties. The violation of Bells inequality offers a meth
od for the certification of quantum links without knowing the inner workings of the devices. Energy-time entanglement quantum communication satisfies all these requirements. However, currently there is a fundamental obstacle with the standard configuration adopted: an intrinsic geometrical loophole that can be exploited to break the security of the communication, in addition to other loopholes. Here we show the first experimental Bell violation with energy-time entanglement distributed over 1 km of optical fibers that is free of this geometrical loophole. This is achieved by adopting a new experimental design, and by using an actively stabilized fiber-based long interferometer. Our results represent an important step towards long-distance secure quantum communication in optical fibers.
We study the relations between quantum coherence and quantum nonlocality, genuine quantum entanglement and genuine quantum nonlocality. We show that the coherence of a qubit state can be converted to the nonlocality of two-qubit states via incoherent
operations. The results are also generalized to qudit case. Furthermore, rigorous relations between the quantum coherence of a single-partite state and the genuine multipartite quantum entanglement, as well as the genuine three-qubit quantum nonlocality are established.
We study the dynamics of genuine multipartite entanglement for quantum systems upto four qubits interacting with general collective dephasing process. Using a computable entanglement monotone for multipartite systems, we observe the feature of freezi
ng dynamics of genuine entanglement for three and four qubits entangled states. We compare the dynamics with that of random states and find that most states exibit this feature. We then study the effects of collective dephasing on genuine nonlocality and find out that although quantum states remain genuinely entangled yet their genuine nonlocality is lost in a finite time. We show the sensitivity of asymptotic states being genuinely entangled by mixing white noise.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
