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We investigate the use of quantum-jump-based feedback to manipulate the stability of multipartite entangled dark states in an open quantum system. Using the model proposed in Phys. Rev. A 76, 010301(R) (2007) for a pair of atoms, we show a…

Quantum Physics · Physics 2015-05-28 R. N. Stevenson , J. J. Hope , A. R. R. Carvalho

Protocols for distributed quantum systems commonly require the simultaneous availability of $n$ entangled states, each with a fidelity above some fixed minimum $F_{\mathrm{app}}$ relative to the target maximally-entangled state. However,…

We demonstrate and contrast two approaches to the stabilization of qubit entanglement by feedback. Our demonstration is built on a feedback platform consisting of two superconducting qubits coupled to a cavity which are measured by a…

Entanglement does not correspond to any observable and its evaluation always corresponds to an estimation procedure where the amount of entanglement is inferred from the measurements of one or more proper observables. Here we address…

Quantum Physics · Physics 2009-11-13 Marco G. Genoni , Paolo Giorda , Matteo G. A. Paris

Quantum thermal machines can generate steady-state entanglement by harvesting spontaneous interactions with local environments. However, using minimal resources and control, the entanglement is typically very noisy. Here, we study…

For quantum systems with high purity, we find all observables that, when continuously monitored, maximize the instantaneous reduction in the von Neumann entropy. This allows us to obtain all locally optimal feedback protocols with strong…

Quantum Physics · Physics 2009-11-13 Alireza Shabani , Kurt Jacobs

Entangled multi-qubit states may be generated through a dispersive collective QND measurement of superconducting qubits coupled to a microwave transmission line resonator. Using the quantum trajectory approach, we analyze the stochastic…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Ferdinand Helmer , Florian Marquardt

Measurement-based heralded entanglement schemes have served as the primary link between physically separated qubits in most quantum information platforms. However, the impossibility of performing a deterministic Bell measurement with linear…

Quantum Physics · Physics 2019-12-03 Leigh S. Martin , K. Birgitta Whaley

This work introduces a self-learning protocol that incorporates measurement and feedback into variational quantum circuits for efficient quantum state preparation. By combining projective measurements with conditional feedback, the protocol…

Quantum Physics · Physics 2025-07-16 Daniel Alcalde Puente , Matteo Rizzi

The correlations of certain entangled quantum states can be fully reproduced via a local model. We discuss in detail the practical implementation of an algorithm for constructing local models for entangled states, recently introduced by…

Quantum Physics · Physics 2018-08-10 Mathieu Fillettaz , Flavien Hirsch , Sébastien Designolle , Nicolas Brunner

We study the verification of maximally entangled states by virtue of the simplest measurement settings: local projective measurements without adaption. We show that optimal protocols are in one-to-one correspondence with complex projective…

Quantum Physics · Physics 2020-01-01 Huangjun Zhu , Masahito Hayashi

We introduce measurement-based quantum repeaters, where small-scale measurement-based quantum processors are used to perform entanglement purification and entanglement swapping in a long-range quantum communication protocol. In the scheme,…

Quantum Physics · Physics 2013-06-03 M. Zwerger , W. Dür , H. J. Briegel

The stochastic evolution of quantum systems during measurement is arguably the most enigmatic feature of quantum mechanics. Measuring a quantum system typically steers it towards a classical state, destroying any initial quantum…

Mesoscale and Nanoscale Physics · Physics 2013-10-18 D. Ristè , M. Dukalski , C. A. Watson , G. de Lange , M. J. Tiggelman , Ya. M. Blanter , K. W. Lehnert , R. N. Schouten , L. DiCarlo

Fault-tolerant quantum computation can be achieved by creating constant-sized, entangled resource states and performing entangling measurements on subsets of their qubits. Linear optical quantum computers can be designed based on this…

Quantum Physics · Physics 2026-02-03 Brendan Pankovich , Alex Neville , Angus Kan , Srikrishna Omkar , Kwok Ho Wan , Kamil Brádler

Entangled states shared among distant nodes are frequently used in quantum network applications. When quantum resources are abundant, entangled states can be continuously distributed across the network, allowing nodes to consume them…

Quantum Physics · Physics 2024-02-01 Álvaro G. Iñesta , Stephanie Wehner

Despite multipartite entanglement being a global property of a quantum state, a number of recent works have made it clear that it can be quantified using only local measurements. This is appealing because local measurements are the easiest…

Quantum Physics · Physics 2024-09-05 Luke Coffman , Akshay Seshadri , Graeme Smith , Jacob L. Beckey

The main advantage of quantum metrology relies on the effective use of entanglement, which indeed allows us to achieve strictly better estimation performance over the standard quantum limit. In this paper, we propose an analogous method…

Quantum Physics · Physics 2017-06-13 Naoki Yamamoto , Tomoaki Mikami

The efficient and reliable characterization of quantum states plays a vital role in most, if not all, quantum information processing tasks. In this work, we present a universally optimal protocol for verifying entangled states by employing…

Quantum Physics · Physics 2021-03-08 Ye-Chao Liu , Jiangwei Shang , Rui Han , Xiangdong Zhang

We introduce novel schemes for quantum computing based on local measurements on entangled resource states. This work elaborates on the framework established in [Phys. Rev. Lett. 98, 220503 (2007), quant-ph/0609149]. Our method makes use of…

Quantum Physics · Physics 2009-11-13 D. Gross , J. Eisert , N. Schuch , D. Perez-Garcia

We investigate measurement-based quantum communication with noisy resource states that are generated by entanglement purification. We consider the transmission of encoded information via noisy quantum channels using a measurement-based…

Quantum Physics · Physics 2017-01-04 Julius Wallnöfer , Wolfgang Dür