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The achievement of quantum supremacy boosted the need for a robust medium of quantum information. In this task, higher-dimensional qudits show remarkable noise tolerance and enhanced security for quantum key distribution applications.…

Quantum volume (QV) has become the de-facto standard benchmark to quantify the capability of Noisy Intermediate-Scale Quantum (NISQ) devices. While QV values are often reported by NISQ providers for their systems, we perform our own series…

Quantum Physics · Physics 2023-08-22 Elijah Pelofske , Andreas Bärtschi , Stephan Eidenbenz

We report on the experimental observation and characterization of a six-photon entangled Dicke state. We obtain a fidelity as high as 0.654$\pm$0.024 and prove genuine six-photon entanglement by, amongst others, a two-setting witness…

Entanglement allows for the nonlocality of quantum theory, which is the resource behind device-independent quantum information protocols. However, not all entangled quantum states display nonlocality, and a central question is to determine…

Quantum Physics · Physics 2016-11-09 Daniel Cavalcanti , Leonardo Guerini , Rafael Rabelo , Paul Skrzypczyk

Quantum state tomography (QST) is plagued by the ``curse of dimensionality'' due to the exponentially-scaled complexity in measurement and data post-processing. Efficient QST schemes for large-scale mixed states are currently missing. In…

Quantum Physics · Physics 2023-08-15 Wen-jun Li , Kai Xu , Heng Fan , Shi-ju Ran , Gang Su

Variational algorithms have received significant attention in recent years due to their potential to solve practical problems using noisy intermediate-scale quantum (NISQ) devices. A fundamental step of these algorithms is the evaluation of…

The development of complex circuits for practical applications in the current quantum computing ecosystem is based on basic primitives such as Bell states, which provide superposition, entanglement, and coherence. The range of…

Quantum Physics · Physics 2026-04-07 Hillol Biswas

The conventional method for generating entangled states in qubit systems relies on applying precise two-qubit entangling gates alongside single-qubit rotations. However, achieving high-fidelity entanglement demands high accuracy in…

Manipulating entanglement, which reflects non-local correlations in a quantum system and defines the complexity of describing its wave function, represents the extremely tough challenge in the fields of quantum computing, quantum…

Evaluating the reliability of noisy quantum circuits is essential for implementing quantum algorithms on noisy quantum devices. However, current quantum hardware exhibits diverse noise mechanisms whose compounded effects make accurate and…

Quantum Physics · Physics 2026-02-23 Jindi Wu , Tianjie Hu , Qun Li

We derive fidelity benchmarks for the quantum storage and teleportation of squeezed states of continuous variable systems, for input ensembles where the degree of squeezing $s$ is fixed, no information about its orientation in phase space…

Quantum Physics · Physics 2009-11-13 M. Owari , M. B. Plenio , E. S. Polzik , A. Serafini , M. M. Wolf

We analyze robustness of correlations of the $N$-qubit GHZ and Dicke states against white noise admixture. For sufficiently large $N$, the Dicke states (for any number of excitations) lead to more robust violation of local realism than the…

Quantum Physics · Physics 2015-11-04 Wieslaw Laskowski , Tamas Vertesi , Marcin Wiesniak

Quantum computing potentially offers exponential speed-ups over classical computing for certain tasks. A central, outstanding challenge to making quantum computing practical is to achieve fault tolerance, meaning that computations of any…

Quantum Physics · Physics 2021-02-01 Jacob Hastrup , Kimin Park , Jonatan Bohr Brask , Radim Filip , Ulrik Lund Andersen

We analyse the use of entangled states to perform quantum computations non locally among distant nodes in a quantum network. The complexity associated with the generation of multiparticle entangled states is quantified in terms of the…

Quantum Physics · Physics 2009-10-31 J. I. Cirac , A. Ekert , S. F. Huelga , C. Macchiavello

Atom-like emitters in solids are promising platforms for quantum sensing and information processing, but inhomogeneities in the emitter fine structure complicate quantum control. We present a framework that leverages this diversity to…

Quantum Physics · Physics 2025-09-04 Pratyush Anand , Louis Follet , Odiel Hooybergs , Dirk R. Englund

Quantum information technologies require careful control for generating and preserving a desired target quantum state. The biggest practical obstacle is, of course, decoherence. Therefore, the reachability analysis, which in our scenario…

Quantum Physics · Physics 2019-05-30 Kohei Kobayashi , Naoki Yamamoto

Measurement-based quantum computing is an alternative paradigm to the circuit-based model. This approach can be advantageous in certain scenarios, such as when read-out is fast and accurate, but two-qubit gates realized via inter-particle…

Quantum Physics · Physics 2021-11-16 Zhangjie Qin , Woo-Ram Lee , Brian DeMarco , Bryce Gadway , Svetlana Kotochigova , V. W. Scarola

Characterizing entanglement of systems composed of multiple particles is a very complex problem that is attracting increasing attention across different disciplines related to quantum physics. The task becomes even more complex when the…

Quantum Physics · Physics 2026-02-12 Shuheng Liu , Qiongyi He , Marcus Huber , Giuseppe Vitagliano

Finding ways to test the behaviour of quantum devices is a timely enterprise, especially in the light of the rapid development of quantum technologies. Device-independent self-testing is one desirable approach, as it makes minimal…

Quantum Physics · Physics 2018-09-26 Ivan Šupić , Andrea Coladangelo , Remigiusz Augusiak , Antonio Acín

A state in a d-dimensional Hilbert space can be simulated by a state defined in a different dimension with high fidelity. We assess how faithfully such the approximated state can perform quantum protocols, using an example of the squeezed…

Quantum Physics · Physics 2009-11-13 Petr Marek , M. S. Kim
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