Article
Optics
D. Bhatti, M. Bojer, J. von Zanthier
Summary: Studied intensity distribution of two identical two-level atoms prepared either in entangled Dicke state or in separable atomic state with nonvanishing dipole moment. Found that both configurations produce similar far-field intensity patterns, though they have fundamentally distinct types of coherence.
Article
Optics
Mario Boneberg, Igor Lesanovsky, Federico Carollo
Summary: Characterizing quantum correlations near phase transitions in open quantum many-body systems is challenging. In this study, the superradiant phase transition of the open quantum Dicke model is examined, showing that local dissipation unexpectedly enhances collective quantum correlations and leads to the emergence of entanglement between the bosonic and spin degrees of freedom in the Dicke model.
Article
Optics
Y. Chew, T. Tomita, T. P. Mahesh, S. Sugawa, S. de Leseleuc, K. Ohmori
Summary: Rydberg atoms show promise for ultrafast quantum operations, but strong interactions between single atoms have been challenging to harness. The authors introduce novel techniques to trap and cool atoms, and use laser pulses to excite them to a Rydberg state. Ultrafast energy exchange and conditional phase are observed.
Article
Physics, Multidisciplinary
Michael Meth, Viacheslav Kuzmin, Rick van Bijnen, Lukas Postler, Roman Stricker, Rainer Blatt, Martin Ringbauer, Thomas Monz, Pietro Silvi, Philipp Schindler
Summary: In this study, a method for implementing quantum-encoded tensor-network (TN) states on an ion-trap quantum computer is proposed, with the ground states of the extended Su-Schrieffer-Heeger model as a case study. The generated states are characterized and verified to possess topological order through estimation of topological invariants.
Article
Optics
Wojciech Roga, Rikizo Ikuta, Tomoyuki Horikiri, Masahiro Takeoka
Summary: We analyze the generation of entanglement in a multipartite optical network and propose a protocol with advantageous rate-loss scalings. We provide theoretical formulas and performance analyses for distributing W states and Dicke states over star networks. We also study the feasibility of the protocol using Gaussian states as resources in realistic experimental conditions.
Article
Optics
Pragna Das, Auditya Sharma
Summary: The Dicke model explores various phase transitions, including quantum phase transitions from normal phase to super-radiant phase and thermal phase transitions. The ground state in the super-radiant phase exhibits multifractality, and the level statistics in the excited-state quantum phase transition show distinct behaviors.
Article
Optics
M. Bojer, J. von Zanthier
Summary: It has been discovered that fully excited two-level atoms can cooperatively emit light in a phenomenon called superradiance. The intensity of the superradiant burst is proportional to the square of the number of atoms, and the temporal width is reduced. Recent studies have shown that the peak intensity is due to the quantum correlations among the atoms when occupying symmetric Dicke states. The temporal evolution of the ensemble is investigated in two scenarios: when the atoms are closely spaced and when they are far apart. It is found that a similar superradiant burst occurs if the quantum correlations are generated by conditional photon measurements retaining the atomic ensemble within or close to the symmetric subspace.
Article
Optics
Vladimir M. Stojanovie, Julian K. Nauth
Summary: This paper focuses on the engineering of the two-excitation Dicke state ID32) in a three-qubit system with all-to-all Ising-type qubit-qubit interaction and global transverse control fields. A pulse sequence is proposed, consisting of three instantaneous control pulses and two finite-duration Ising-interaction pulses, based on the concept of the symmetric sector. Numerical analysis is conducted to demonstrate the robustness of the proposed state-preparation scheme to systematic errors. The generalization of this scheme to systems with N > 4 qubits is also discussed.
Article
Multidisciplinary Sciences
Marcin Wiesniak
Summary: The study focuses on the persistence of Bell correlations in GHZ based mixtures and Dicke states. New Bell inequalities are proposed for the quantum communication complexity reduction scheme, leading to higher persistence in the limit of a large number of particles N. The research shows that the persistence of Dicke states can reach 0.482N, significantly higher than previously reported.
SCIENTIFIC REPORTS
(2021)
Article
Optics
Wen-Hao Zhou, Zhi-Qiang Jiao, Hang Li, Jun Gao, Xiao-Wei Wang, Ruo-Jing Ren, Xiao-Yun Xu, Lu-Feng Qiao, Xian-Min Jin
Summary: Researchers propose and experimentally demonstrate heralded multipartite entanglements on a three-dimensional photonic chip. By controlling the coherent evolution of a single photon in multiple spatial modes, they dynamically tune the high-order W-states of different orders in a single photonic chip. Using an effective witness, they observe and verify 61-partite quantum entanglements in a 121-site photonic lattice. These results offer insights into the accessible size of quantum entanglements and may advance large-scale quantum information processing applications.
Article
Physics, Multidisciplinary
Leizhen Chen, Liangliang Lu, Lijun Xia, Yanqing Lu, Shining Zhu, Xiao-song Ma
Summary: Integrated quantum photonics is a rapidly developing field that allows for the generation, manipulation, and detection of entangled photons. Multipartite entangled states, such as the Dicke states, are essential for scalable quantum information processing. In this study, we demonstrate the generation and coherent control of four-photon Dicke states using a silicon photonic chip. The generated photons are in the telecom band, making them suitable for large-scale photonic quantum technologies for multiparty networking and metrology.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
S. I. Mukhin, A. Mukherjee, S. S. Seidov
Summary: Analytic expression for the frequency dependence of transmission coefficient of microwave cavity coupled to transmission line with superradiant condensate is obtained, showing sharp transmission drops that reflect the condensate's frequencies spectrum. These findings pave the way for direct detection of the emergence of superradiant condensates in quantum metamaterials. The results are based on the analytic solutions of the nonlinear semiclassical dynamics of superradiant photonic condensate in the Dicke model, which describes ensemble of dipolar-coupled two-level atoms to electromagnetic field in the microwave cavity. In the ground state, the semiclassical coordinate of the superradiant condensate either oscillates in one of the two degenerate minima of its potential energy or traverses between them over the saddle point, depending on the coupling strength. An experimental setup is proposed for measuring the breakdown of the normal phase of the Dicke model through coupling with the transmission line. Additionally, the semiclassical motion of the superradiant condensate can be mapped to the nodding of an unstable LaGrange sleeping top, making the Dicke model an analog device for modeling mechanical systems dynamics.
Article
Optics
Rodolfo R. Soldati, Mark T. Mitchison, Gabriel T. Landi
Summary: In this study, multipartite correlations in a generalized Dicke model involving two optical modes interacting with an ensemble of two-level atoms are analyzed. The results show the existence of genuine tripartite entanglement in the vicinity of the critical lines, where quantum correlations are shared between the atoms and the two modes.
Article
Physics, Multidisciplinary
Bartosz Regula
Summary: This paper presents a new resource monotone that can rule out all transformations, probabilistic or deterministic, between states in any quantum resource theory. The results obtained from this approach provide significant improvements for probabilistic distillation protocols, allowing for better error and overhead bounds. The monotone also serves as a necessary and sufficient condition for state convertibility.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Nidhin Prasannan, Jan Sperling, Benjamin Brecht, Christine Silberhorn
Summary: We report on the nonlinear squeezing effects of polarization states of light achieved by utilizing click-counting measurements and the intrinsic correlations of a polarization-entangled light source. By deriving theoretical bounds for nonlinear Stokes operators and developing an efficient light source and detection system, we experimentally validate our theoretical predictions and demonstrate highly statistically significant nonclassical correlations.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
A. Hueper, C. Puer, M. Hetzel, J. Geng, J. Peise, I Kruse, M. Kristensen, W. Ertmer, J. Arlt, C. Klempt
Summary: The article discusses an accurate technique for determining the number of atoms in entangled atomic ensembles, which is essential for interferometry beyond the standard quantum limit. The fluorescence detection method presented allows for single-atom accuracy measurements, with extrapolated accuracy for up to 390 atoms. This accurate atom number detection is utilized for stabilizing laser-cooled atomic ensembles and achieving high preparation fidelity and low number fluctuations below shot noise level in a target ensemble of 7 atoms.
NEW JOURNAL OF PHYSICS
(2021)
Article
Quantum Science & Technology
Paul Appel, Alexander J. Heilman, Ezekiel W. Wertz, David W. Lyons, Marcus Huber, Matej Pivoluska, Giuseppe Vitagliano
Summary: This paper introduces the finite-function-encoding (FFE) states and investigates their structural properties. It compares the differences between polynomial and non-polynomial function encoding states and introduces the concept of finite-function-encoding Pauli (FP) operators. The paper studies the stabilizer group and classification of FFE states under local unitaries (LU), focusing on bipartite states and their classification under local FP operations (LFP), and also discusses the relation between FFE states and the theory of finite rings over the integers.
Article
Quantum Science & Technology
Giuseppe Vitagliano, Matteo Fadel, Iagoba Apellaniz, Matthias Kleinmann, Bernd Lucke, Carsten Klempt, Geza Toth
Summary: This article presents a method to detect bipartite entanglement using number-phase-like uncertainty relations in split spin ensembles. An uncertainty relation is derived for spin systems, which allows for the detection of bipartite entanglement in an unpolarized Dicke state of many spin1/2 particles. The method involves splitting the particles into two subensembles and conducting collective angular momentum measurements locally on each part.
Article
Quantum Science & Technology
Shuheng Liu, Qiongyi He, Marcus Huber, Otfried Guhne, Giuseppe Vitagliano
Summary: We propose a method to detect the dimensionality of entanglement using correlations between measurements in randomized directions. By deriving an inequality based on the covariance matrix criterion, which is invariant under local changes of su(d) bases, we can find regions in the space of randomized correlations moments that determine the different dimensionalities of entanglement. Our method shows promising results in practical scenarios and can detect more states than existing criteria, making it a powerful and potentially simpler approach. Future work should focus on implementing this method in multipartite scenarios.
Article
Quantum Science & Technology
Philip Taranto, Faraj Bakhshinezhad, Andreas Bluhm, Ralph Silva, Nicolai Friis, Maximilian P. E. Lock, Giuseppe Vitagliano, Felix C. Binder, Tiago Debarba, Emanuel Schwarzhans, Fabien Clivaz, Marcus Huber
Summary: Thermodynamics links our understanding of the world to our ability to manipulate and control it. The third law of thermodynamics and Nernst's unattainability principle highlight the need for infinite resources to cool a system to absolute zero temperature. This study provides a framework for identifying the resources required for creating pure quantum states, and extends Landauer's principle to a thermodynamic setting. It emphasizes the importance of control and demonstrates the connection between information and thermodynamics.
Article
Optics
Giuseppe Vitagliano, Costantino Budroni
Summary: Leggett and Garg formulated macrorealist models to test macroscopic quantum coherence effects, but these tests are subject to loopholes. This review discusses recent progress in characterizing macrorealist and quantum temporal correlations, closing the loopholes associated with Leggett-Garg tests, and introduces definitions of nonclassical temporal correlations and their applications in sequential quantum information processing.
Article
Optics
Cebrail Puer, Mareike Hetzel, Martin Quensen, Andreas Hueper, Jiao Geng, Jens Kruse, Wolfgang Ertmer, Carsten Klempt
Summary: In this paper, a high-flux source of 87Rb Bose-Einstein condensates combined with a number-resolving detection is presented for state tomography and interferometric application of entangled quantum states. A hybrid evaporation approach in a magnetic and optical trap is used to create Bose-Einstein condensates of 2 x 105 atoms with minimal thermal fraction within 3.3 s. The low-noise selection and subsequent detection of subsamples of up to 16 atoms are demonstrated, with counting noise below 0.2 atoms. These techniques offer an exciting path towards creating and analyzing mesoscopic quantum states with improved fidelities and their applications in fundamental and metrological fields.
Article
Physics, Multidisciplinary
Ferenc Igloi, Geza Toth
Summary: We use entanglement witnesses to detect and analyze entanglement in the XY chain at thermal equilibrium. Different types of entanglement witnesses, based on the Hamiltonian and entanglement negativity, are considered and tested in both infinite and finite systems. The results show the efficiency of energy-based entanglement witnesses in detecting nearest-neighbor entanglement in spin chains. Furthermore, the usefulness of our method is demonstrated analytically by determining the domains in parameter space corresponding to entangled postquench states detected by the energy-based witness.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Quantum Science & Technology
Geza Toth, Jozsef Pitrik
Summary: In this study, the quantum Wasserstein distance is defined and its properties are examined by optimizing bipartite separable states. Surprisingly, it is found that the self-distance is related to the quantum Fisher information. A transport map corresponding to an optimal bipartite separable state is presented. The introduced quantum Wasserstein distance is discussed in relation to criteria detecting quantum entanglement. Variance-like quantities are defined by replacing the minimization over quantum states with a maximization, and the results are extended to a family of generalized quantum Fisher information quantities.
Article
Physics, Multidisciplinary
Magnus G. Skou, Kristian K. Nielsen, Thomas G. Skov, Andreas M. Morgen, Nils B. Jorgensen, Arturo Camacho-Guardian, Thomas Pohl, Georg M. Bruun, Jan J. Arlt
Summary: Spectroscopic and interferometric measurements are essential for extracting the fundamental properties of quantum many-body systems. Interferometry can elucidate the dynamical evolution of the system, while spectroscopy provides precise measurements of equilibrated energies. The comparison of interferometric and spectroscopic timescales in the study of the Bose polaron reveals important insights into the quasiparticle physics.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Geza Toth, Florian Froewis
Summary: We present several inequalities related to the Robertson-Schrodinger uncertainty relation. By considering a decomposition of the density matrix and using the fact that the uncertainty relation is valid for all components, we derive an alternative method and list the conditions needed to saturate the inequality. We also provide formulations involving the variance and show an improvement of the uncertainty relation.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Costantino Budroni, Giuseppe Vitagliano, Mischa P. Woods
Summary: The study finds that quantum correlations in ticking clock models can surpass classical bounds, violating Leggett-Garg-type temporal inequalities for finite sequences without requiring input.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Quantum Science & Technology
Marek Gluza, Joao Sabino, Nelly H. Y. Ng, Giuseppe Vitagliano, Marco Pezzutto, Yasser Omar, Igor Mazets, Marcus Huber, Jorg Schmiedmayer, Jens Eisert
Summary: This study introduces a blueprint for quantum field machines, which aims to address the lack of experimental implementations of thermal machines in the quantum regime. The concept is very general and can be implemented in many-body quantum systems, with a detailed proposal for realization in one-dimensional ultracold atomic gases. Iterative numerical modeling of operational primitives leads to the design of complete quantum thermodynamic cycles capable of active cooling, showing potential in exploring open questions in quantum information and dynamics.
