Quantum simulations of localization effects with dipolar interactions

Álvarez, Gonzalo; Kaiser, Robin; Suter, Dieter

doi:10.1002/andp.201300096

Cited by 23 publications

(35 citation statements)

References 76 publications

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“…Without perturbation the cluster-size is expected to grow with a power law in agreement with several experimental observations in solid-state spin-networks (44). In our system, this growth law is also observed for times t 0.7ms and vanishing perturbation p = 0, where K ∝ t 4.3 (38,39).…”

Section: Finite-time Scalingsupporting

confidence: 91%

“…. Such elements ρ ij are called ∆M z quantum coherences and can be quantified by the multiple quantum coherence (MQC) spectrum A(∆M z ) given by the amplitude of coherences of the density matrix for a given ∆M z (38,39,43). The time evolution of the MQC spectrum is shown in the insets of Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Here, we use nuclear magnetic resonance (NMR), which provides a natural and versatile approach for coherently controlling large numbers of spins (up to ∼ 7000) in solid state systems, where dipolar interactions are present. NMR techniques allow to quantify the number of spins that are coherently correlated, and allow control of the interaction types and strengths of the Hamiltonians (37)(38)(39).…”

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confidence: 99%

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Localization-delocalization transition in the dynamics of dipolar-coupled nuclear spins

Álvarez

Suter

Kaiser

2015

Science

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144

159

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Non-equilibrium dynamics of many-body systems is important in many branches of science, such as condensed matter, quantum chemistry, and ultracold atoms. Here we report the experimental observation of a phase transition of the quantum coherent dynamics of a 3D many-spin system with dipolar interactions, and determine its critical exponents. Using nuclear magnetic resonance (NMR) on a solid-state system of spins at room-temperature, we quench the interaction Hamiltonian to drive the evolution of the system. The resulting dynamics of the system coherence can be localized or extended, depending on the quench strength. Applying a finite-time scaling analysis to the observed time-evolution of the number of correlated spins, we extract the critical exponents ν ≈ s ≈ 0.42 around the phase transition separating a localized from a delocalized dynamical regime. These results show clearly that such nuclear-spin based quantum simulations can effectively model the non-equilibrium dynamics of complex many-body systems, such as 3D spin-networks with dipolar interactions.The complexity of many-body systems is a long standing problem in physics (1-8). As an example, quantum states of many-body systems can be localized at well defined positions in space or they can be delocalized, depending on parameters like disorder. In their localized regime, such systems may not reach a thermal state but retain information about their initial state on very long timescales (9-17). The role of the topology, dimension, long and short range interactions, and the presence of disorder is very important for the onset of these localization regimes. Much progress was achieved on the numerical and theoretical side, where these phenomena have been predicted under certain conditions. However, experimentally addressing 3D manybody systems in a controlled manner poses severe experimental problems (5,8,14,16). Non-equilibrium dynamics of many-body systems has been investigated to provide complementary information about a large variety of situations but also remains challenging (18-26). Therefore, finding different experimental situations, new approaches and techniques for controlling and observing many-body dynamics can lead to new approaches for studying manybody physics.The recent progress on the experimental control of cold atoms (6, 27, 28), trapped ions (25, 26, 29, 30), Rydberg atoms (31), polar molecules (7, 32) and nitrogen-vacancy centers in diamond (33-36) has led to promising new ways of studying the non-equilibrium dynamics and localization phenomena of many-body systems. In particular a lot of effort is focused on studying many-spin systems with dipolar interactions of the Heisenberg-type (8, 24-26, 31, 32). Here, we use nuclear magnetic resonance (NMR), which provides a natural and versatile approach for coherently controlling large numbers of spins (up to ∼ 7000) in solid state systems, where dipolar interactions are present. NMR techniques allow to quantify the number of spins that are coherently correlated, and allow control of the interact...

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Section: Finite-time Scalingsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Localization-delocalization transition in the dynamics of dipolar-coupled nuclear spins

Álvarez

Suter

Kaiser

2015

Science

Self Cite

144

159

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“…In other scenarios, power-law tails can also characterize charge diffusion in conducting crystals [55] or spin diffusion in complex spin-networks [23,24,54,63]. Generalized Ohmic spectra may help understanding the functioning of nanoscale electromechanical devices [64], as well as superconducting devices attached to conducting leads [65].…”

Section: Discussionmentioning

confidence: 99%

Maximizing Information on the Environment by Dynamically Controlled Qubit Probes

2016

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We explore the ability of a qubit probe to characterize unknown parameters of its environment. By resorting to quantum estimation theory, we analytically find the ultimate bound on the precision of estimating key parameters of a broad class of ubiquitous environmental noises ("baths") which the qubit may probe. These include the probe-bath coupling strength, the correlation time of generic bath spectra, the power laws governing these spectra, as well as their dephasing times T2. Our central result is that by optimizing the dynamical control on the probe under realistic constraints one may attain the maximal accuracy bound on the estimation of these parameters by the least number of measurements possible. Applications of this protocol that combines dynamical control and estimation theory tools to quantum sensing are illustrated for a nitrogen-vacancy center in diamond used as a probe.

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“…In many applications, the second coherence order plays an important role since it indicates only spin pairs interacting through the residual dipolar coupling, which allows one to estimate the average distance between coupled spins in an amorphous solid [37][38][39]. Furthermore, when simulating localization effects induced by decoherence through a spin counting experiment [40][41][42][43], one can verify the number of correlated spins measuring the distribution of the signal among all coherence orders.…”

mentioning

confidence: 99%

Coherence orders, decoherence, and quantum metrology

et al. 2018

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Since the dawn of quantum theory, coherence has been attributed as a key to understand the weirdness of fundamental concepts such as, e.g., the wave-particle duality and the Stern-Gerlach experiment. Recently, based on a resource theory approach, the notion of quantum coherence was revisited and a plethora of coherence quantifiers was proposed. In this work, we address such issue employing the language of coherence orders developed by the NMR community. This allowed us to investigate the role played by different subspaces of the Hilbert-Schmidt space into physical processes and quantum protocols. We found some links between decoherence and each coherence order. Moreover, we propose a sufficient and straightforward method to testify the usefulness of a given state for quantum enhanced phase estimation, relying on a minimal set of elements belonging to the density matrix.

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Quantum simulations of localization effects with dipolar interactions

Cited by 23 publications

References 76 publications

Localization-delocalization transition in the dynamics of dipolar-coupled nuclear spins

Localization-delocalization transition in the dynamics of dipolar-coupled nuclear spins

Maximizing Information on the Environment by Dynamically Controlled Qubit Probes

Coherence orders, decoherence, and quantum metrology

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