Yafei Yu, Jian Feng, Mingsheng Zhan
In this short note, we propose a scheme, in which two instances of an equatorial state (or a polar state) can be remotely prepared in one-shot operation to different receivers with prior entanglement and 1 bit of broadcasting. The trade-off curve between the amount of entanglement and the achievable fidelity is derived.
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。
继续探索
Recently, several similar protocols[J. Opt. B 4 (2002) 380; Phys. Lett. A 316 (2003) 159; Phys. Lett. A 355 (2006) 285; Phys. Lett. A 336 (2005) 317] for remotely preparing a class of multi-qubit states (i.e, $α|0 ... 0>+β|1... 1>$) are proposed, respectively. In this paper, by applying the controlled-not (CNOT) gate, a new simple protocol is proposed for remotely preparing such class of states. Compared to the previous protocols, both classical communication cost and required quantum entanglement in our protocol are remarkably reduced. Moreover, the difficulty of identifying some quantum stat…
Remotely Preparing Many Qubits with a Single Photon
该研究利用单光子在多个模式中的叠加，实现远程量子态准备的量子加速，通过反射基于协议在多个变体中实现，提高多量子比特准备的成功率和保真度。
Optical downconversion is a key resource for generating nonclassical states. Very recently, direct nondegenerate triple-photon spontaneous downconversion (NTPSD) with bright photon triplets and strong third-order correlations has been demonstrated in a superconducting device (2020 Phys. Rev. X 10 011011). Besides, linear and nonlinear tripartite entanglement in this process have also been predicted (2018 Phys. Rev. Lett. 120 043601; 2020 Phys. Rev. Lett. 125 020502). In this paper, we consider the generation of nonclassical optical quantum superpositions and investigate nonlinear quantum steer…
Among the possibly most intriguing aspects of quantum entanglement is that it comes in "free" and "bound" instances. Bound entangled states require entangled states in preparation but, once realized, no free entanglement and therefore no pure maximally entangled pairs can be regained. Their existence hence certifies an intrinsic irreversibility of entanglement in nature and suggests a connection with thermodynamics. In this work, we present a first experimental unconditional preparation and detection of a bound entangled state of light. We consider continuous-variable entanglement, use convex …
Preparing Remote States for Genuine Quantum Networks
提出并实验验证RSP能力这一量子资源，用以刻画真正量子网络中远程态制备超越经典模拟所需的静态与动态条件。
How to uses shared entanglement and forward classical communication to remotely prepare an arbitrary (mixed or pure) state has been fascinating quantum information scientists. A constructive scheme has been given by Berry for remotely preparing a general pure state with a pure entangled state and finite classical communication. Based on this scheme, for high-dimensional systems it is possible to use a coding of the target state to optimize the classical communication cost. Unfortunately, for low-dimensional systems such as a pure qubit the coding method is inapplicable. Because qubit plays a c…
Quantum computers will be able solve important problems with significant polynomial and exponential speedups over their classical counterparts, for instance in option pricing in finance, and in real-space molecular chemistry simulations. However, key applications can only achieve their potential speedup if their inputs are prepared efficiently. We effectively solve the important problem of efficiently preparing quantum states following arbitrary continuous (as well as more general) functions with complexity logarithmic in the desired resolution, and with rigorous error bounds. This is enabled …
Quantum memories are a crucial technology for enabling large-scale quantum networks through synchronisation of probabilistic operations. Such networks impose strict requirements on quantum memory, such as storage time, retrieval efficiency, bandwidth, and scalability. On- and off-resonant ladder protocols on warm atomic vapour platforms are promising candidates, combining efficient high-bandwidth operation with low-noise on-demand retrieval. However, their storage time is severely limited by motion-induced dephasing caused by the broad velocity distribution of atoms comprising the vapour. In t…
Preparing highly entangled quantum states between remote parties is a major challenge for quantum communications [1-8]. Particularly promising in this context are the N00N states, which are entangled N-photon wavepackets delocalized between two different locations, providing measurement sensitivity limited only by the uncertainty principle [1, 10-15]. However, these states are notoriously vulnerable to losses, making it difficult both to share them between remote locations, and to recombine them to exploit interference effects. Here we address this challenge by utilizing the reverse version of…
Users of quantum computers must be able to confirm they are indeed functioning as intended, even when the devices are remotely accessed. In particular, if the Hilbert space dimension of the components are not as advertised -- for instance if the qubits suffer leakage -- errors can ensue and protocols may be rendered insecure. We refine the method of delayed vectors, adapted from classical chaos theory to quantum systems, and apply it remotely on the IBMQ platform -- a quantum computer composed of transmon qubits. The method witnesses, in a model-independent fashion, dynamical signatures of hig…
Remote state preparation of single-partite high-dimensional states in complex Hilbert spaces
本文提出了一种利用正交测量基远程制备复Hilbert空间中高维等价态的方案，并展示了通过调整参数实现不同维度态的可能性。
The variational preparation of complex quantum states using the quantum approximate optimization algorithm (QAOA) is of fundamental interest, and becomes a promising application of quantum computers. Here, we systematically study the performance of QAOA for preparing ground states of target Hamiltonians near the critical points of their quantum phase transitions, and generating Greenberger-Horne-Zeilinger (GHZ) states. We reveal that the performance of QAOA is related to the translational invariance of the target Hamiltonian: Without the translational symmetry, for instance due to the open bou…
Similarity-Based Parameter Transferability in the Quantum Approximate Optimization Algorithm
本文通过揭示QAOA最优参数的聚类规律，提出基于图局部性质（光锥子图类型和节点奇偶性）的参数迁移方法，实现供体图参数向更大受体图的有效复用，从而加速变分量子算法求解组合优化问题。
Improving Generalization and Trainability of Quantum Eigensolvers via Graph Neural Encoding
本文提出一种结合图自编码器和经典神经网络的端到端框架，提升量子本征求解器的泛化能力和训练效率，通过编码相互作用拓扑结构，减少对实例特定优化的依赖，提高收敛速度和稳定性。
Circumventing superexponential runtimes for hard instances of quantum adiabatic optimization
针对最大独立集问题绝热量子优化中最小能隙超指数衰减导致求解时间过长的问题，提出利用量子猝灭产生的量子多体疤痕效应，从次优构型制备高基态重叠度的态以规避超指数运行时间。
Arbitrary state preparation in quantum harmonic oscillators using neural networks
提出一种基于神经网络的方法，通过驱动与辅助量子比特耦合的量子谐振子，直接生成控制参数以制备任意量子态，无需逐实例优化，实现了高保真度制备。
We compare two different implementations of fault-tolerant entangling gates on logical qubits. In one instance, a twelve-qubit trapped-ion quantum computer is used to implement a non-transversal logical CNOT gate between two five qubit codes. The operation is evaluated with varying degrees of fault tolerance, which are provided by including quantum error correction circuit primitives known as flagging and pieceable fault tolerance. In the second instance, a twenty-qubit trapped-ion quantum computer is used to implement a transversal logical CNOT gate on two [[7,1,3]] color codes. The two codes…
Nishimori's cat: stable long-range entanglement from finite-depth unitaries and weak measurements
研究监测量子电路中弱测量下长程纠缠的稳定性，提出确定性电路协议制备二维猫态与三维toric code，并证明其在二维和三维空间中保持稳定且可在现有量子架构上实现。
Experimental studies of synthetic quantum matter are necessarily restricted to approximate ground states prepared on finite-size quantum simulators. In general, this limits their reliability for strongly correlated systems, for instance, in the vicinity of a quantum phase transition (QPT). Here, we propose a protocol that makes optimal use of a given finite-size simulator by directly preparing, on its bulk region, a mixed state representing the reduced density operator of the translation-invariant infinite-sized system of interest. This protocol is based on coherent evolution with a local defo…
A Quantum Approximate Optimization Algorithm for Local Hamiltonian Problems
本研究针对局部哈密顿量问题中的量子最大割问题，提出基于组合优化方案的HamQAOA算法，给出性能保证与参数优化策略，实验表明其在多类实例上优于现有算法，且线性深度即可制备贝特态。
Markovian dephasing has no entanglement-breaking threshold, and a fixed tolerance will report one anyway
本文研究了在三层量子脑模型中，协变量子纠错对不同层相干动力学的影响，通过比较两种蛋白质的相干时间，探讨了纠错对维持量子相干性的效果。
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。