Probing many-body dynamics in a two dimensional dipolar spin ensemble

Abstract

The most direct approach for characterizing the quantum dynamics of a strongly-interacting system is to measure the time-evolution of its full many-body state. Despite the conceptual simplicity of this approach, it quickly becomes intractable as the system size grows. An alternate framework is to think of the many-body dynamics as generating noise, which can be measured by the decoherence of a probe qubit. Our work centers on the following question: What can the decoherence dynamics of such a probe tell us about the many-body system? In particular, we utilize optically addressable probe spins to experimentally characterize both static and dynamical properties of strongly-interacting magnetic dipoles. Our experimental platform consists of two types of spin defects in diamond: nitrogen-vacancy (NV) color centers (probe spins) and substitutional nitrogen impurities (many-body system). We demonstrate that signatures of the many-body system's dimensionality, dynamics, and disorder are naturally encoded in the functional form of the NV's decoherence profile. Leveraging these insights, we directly characterize the two-dimensional nature of a nitrogen delta-doped diamond sample. In addition, we explore two distinct facets of the many-body dynamics: First, we address a persistent debate about the microscopic nature of spin dynamics in strongly-interacting dipolar systems. Second, we demonstrate direct control over the spectral properties of the many-body system, including its correlation time. Our work opens the door to new directions in both quantum sensing and simulation.

Glassy quantum dynamics of disordered Ising spins

“…Recently, glassy dynamics has been found to emerge in disordered systems in a regime where a quantum mechanical description is required. In experiments with nitrogen-vacancy centers in diamond [6][7][8] and in manybody localized systems under the influence of dissipation [9] sub-exponential relaxation dynamics was observed. These studies consider the dynamics of open quantum systems where dissipation arising from coupling to an external bath explains the slow relaxation.…”

The Measurement-induced Transition in Long-range Interacting Quantum Circuits

“…First, such long-range interactions are known to have profound effects on the universality, and indeed, even the existence, of many phase transitions [39][40][41][42][43][44]; in addition, long-range interactions can parametrically alter the form of Lieb-Robinson bounds and scrambling lightcones [45][46][47][48]. Second, many of the most promising experimental platforms for investigating the measurementinduced transition, including Rydberg tweezer arrays, polar molecules, trapped ions and solid-state magnetic dipoles, inherently feature long-range interactions [49][50][51][52][53].…”

Intrinsic and induced quantum quenches for enhancing qubit-based quantum noise spectroscopy

“…As we will show in Eqs. (24) and (26b), this also encompasses the case of more general forms of quench operator V beyond Eq. ( 4), corresponding to a wide number of T 2 -based sensing protocols with generic initial bath states.…”

“…Commonly referred to as quantum noise spectroscopy (QNS) [1], this modality allows one to understand and possibly mitigate sources of decoherence that degrade a quantum processor [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. It also serves as a powerful means to probe a complicated manybody target system via its fluctuation properties (see, e.g., [20][21][22][23][24]). While many QNS protocols focus on the more specific problem of characterizing classical Gaussian noise [4][5][6][7][8][9][10][11][12], recent work has explored methods that go beyond these assumptions [13][14][15][16][17][18][19][25][26][27][28][29][30].…”