High-order time crystal phases and their fractal nature

Giachetti, Guido; Solfanelli, Andrea; Correale, Lorenzo; Defenu, Nicoló

doi:10.48550/arxiv.2203.16562

Cited by 5 publications

(6 citation statements)

References 64 publications

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“…2 as well. Interestingly, this mechanism is analogous to the phenomenon of period doubling of Floquet driven systems near to resonances [82][83][84][85][86][87][88][89][90][91][92][93].…”

Section: Single-qubitmentioning

confidence: 81%

Observation of partial and infinite-temperature thermalization induced by repeated measurements on a quantum hardware

et al. 2023

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On a quantum superconducting processor we observe partial and infinite-temperature thermalization induced by a sequence of repeated quantum projective measurements, interspersed by a unitary (Hamiltonian) evolution. Specifically, on a qubit and two-qubit systems, we test the state convergence of a monitored quantum system in the limit of a large number of quantum measurements, depending on the non-commutativity of the Hamiltonian and the measurement observable. When the Hamiltonian and observable do not commute, the convergence is uniform towards the infinite-temperature state. Conversely, whenever the two operators have one or more eigenvectors in common in their spectral decomposition, the state of the monitored system converges differently in the subspaces spanned by the measurement observable eigenstates. As a result, we show that the convergence does not tend to a completely mixed (infinite-temperature) state, but to a block-diagonal state in the observable basis, with a finite effective temperature in each measurement subspace. Finally, we quantify the effects of the quantum hardware noise on the data by modelling them by means of depolarizing quantum channels.

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“…2 as well. Interestingly, this mechanism is analogous to the phenomenon of period doubling of Floquet driven systems near to resonances [82][83][84][85][86][87][88][89][90][91][92][93].…”

Section: Single-qubitmentioning

confidence: 81%

Observation of partial and infinite-temperature thermalization induced by repeated measurements on a quantum hardware

et al. 2023

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“…where |ϕ ± k ⟩ are the instantaneous eigenstates of the Hamiltonian defined in equation (46). The energies E 2 and E 4 at the end of the two unitary strokes of the cycle can then be written as…”

Section: Discussionmentioning

confidence: 99%

“…Long-range interacting systems are emerging as promising platforms for quantum technological applications, due to their stability against external perturbations, which allows for keeping the impact of dynamically generated excitations under control, therefore mitigating their detrimental effects [42]. An example of the rigidity of long-range interacting platforms against external drivings, is the possibility for such systems to host Floquet time crystal phases [43][44][45][46]47]. Moreover, long-range interactions are known to alter the universal behavior of critical systems at and out of equilibrium, generating a wide range of unprecedented phenomena.…”

Section: Introductionmentioning

confidence: 99%

Quantum heat engine with long-range advantages

et al. 2023

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The employment of long-range interactions in quantum devices provides a promising route towards enhancing their performance in quantum technology applications. Here, the presence of long-range interactions is shown to enhance the performances of a quantum heat engine featuring a many-body working substance. We focus on the paradigmatic example of a Kitaev chain undergoing a quantum Otto cycle and show that a substantial thermodynamic advantage may be achieved as the range of the interactions among its constituents increases. Interestingly, such an advantage is most significant for the realistic situation of a finite time cycle: the presence of long-range interactions reduces the non-adiabatic energy losses, by suppressing the detrimental effects of dynamically generated excitations. This effect allows mitigating the trade-off between power and efficiency, paving the way for a wide range of experimental and technological applications.

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“…A decade ago, Wilczek proposed a fascinating idea for a novel phase of matter, dubbed "time crystal", which involves the spontaneous breaking of the continuous timetranslational symmetry of the system [1]. While a number of no-go theorems ruled out the existence of such a phase of matter [2,3], the possibility of breaking a "discrete" time-translation symmetry -realising discrete time crystals (DTC) -has generated a large body of literature [4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Clean two-dimensional Floquet time-crystal

Santini¹,

Santoro²,

Collura³

2022

Preprint

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We consider the two-dimensional quantum Ising model, in absence of disorder, subject to periodic imperfect global spin flips. We show by a combination of exact diagonalization and tensor-network methods that the system can sustain a spontaneously broken discrete time-translation symmetry. Employing careful scaling analysis, we show the feasibility of a two-dimensional discrete time-crystal (DTC) phase. Despite an unbounded energy pumped into the system, in the high-frequency limit, a well-defined effective Hamiltonian controls a finite-temperature intermediate regime, wherein local time averages are described by thermal averages. As a consequence, the long-lived stability of the DTC relies on the existence of a long-range ordered phase at finite temperature. Interestingly, even for large deviations from the perfect spin flip, we observe a non-perturbative change in the decay rate of the order parameter, which is related to the long-lived stability of the magnetic domains in 2D.

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High-order time crystal phases and their fractal nature

Cited by 5 publications

References 64 publications

Observation of partial and infinite-temperature thermalization induced by repeated measurements on a quantum hardware

Observation of partial and infinite-temperature thermalization induced by repeated measurements on a quantum hardware

Quantum heat engine with long-range advantages

Clean two-dimensional Floquet time-crystal

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