Quantum Complexity Dynamics for Disjoint Subsystems

• URL: http://arxiv.org/abs/2609.00126v1
• Date: Mon, 31 Aug 2026 18:00:01 GMT
• Title: Quantum Complexity Dynamics for Disjoint Subsystems
• Abstract summary: We show, using complementary tools from holography and random quantum circuits, that noncontiguous subsystems give rise to qualitatively new physics.<n>First, at finite temperature, a subsystem occupying less than half of the total system can carry high complexity at late times.<n>Second, if a subsystem's complexity equilibrates at an early time, then fragmenting it into $m$ disjoint components can further reduce this timescale.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Quantum complexity has emerged as a natural probe of chaos, thermalization, and the black hole interior on timescales long after local observables have equilibrated. However, its time evolution has been studied almost exclusively in subsystems confined to a single connected region. We show, using complementary tools from holography and random quantum circuits, that noncontiguous subsystems composed of multiple disjoint regions give rise to qualitatively new physics compared to the contiguous case. First, at finite temperature, a subsystem occupying less than half of the total system can carry high complexity at late times, even as the complexity of its larger complement remains low. This inversion of the usual hierarchy is intrinsically thermal: it vanishes in the infinite-temperature limit, which is the regime modeled by random quantum circuits. Second, if a subsystem's complexity equilibrates at an early time, then fragmenting it into $m$ disjoint components can further reduce this timescale by a factor of $m$, a phenomenon we exhibit in both holography and random quantum circuits. These results not only sharpen the correspondence between geometric and computational notions of complexity, but also motivate the search for novel complexity phenomena in quantum dynamics.

Related papers

• State Diagnostics of Complexity in Open Quantum Systems [39.146761527401424]
  We study the emergence of complexity in finite-size quantum systems.<n>We represent mixed quantum states as probability measures on complex projective Hilbert space.
  arXiv  Detail & Related papers  (2026-08-10T15:09:52Z)
• Sharp Transitions for Subsystem Complexity [0.0]
  We study the circuit complexity of time-evolved subsystems of pure quantum states.<n>We find that for greater-than-half subsystem sizes, the complexity grows linearly in time for an exponentially long time.<n>For less-than-half subsystem sizes, the complexity rises and then falls, returning to low complexity as the subsystem equilibrates.
  arXiv  Detail & Related papers  (2025-10-21T17:28:00Z)
• Direct probing of the simulation complexity of open quantum many-body dynamics [42.085941481155295]
  We study the role of dissipation in simulating open-system dynamics using both quantum and classical methods.<n>Our results show that dissipation affects correlation length and mixing time in distinct ways at intermediate and long timescales.
  arXiv  Detail & Related papers  (2025-08-27T15:14:36Z)
• Probing quantum many-body dynamics using subsystem Loschmidt echos [39.34101719951107]
  We experimentally investigate the subsystem Loschmidt echo, a quasi-local observable that captures key features of the Loschmidt echo.<n>In the short-time regime, we observe a dynamical quantum phase transition arising from genuine higher-order correlations.<n>In the long-time regime, the subsystem Loschmidt echo allows us to quantitatively determine the effective dimension and structure of the accessible Hilbert space in the thermodynamic limit.
  arXiv  Detail & Related papers  (2025-01-28T14:51:37Z)
• Time-dependent Neural Galerkin Method for Quantum Dynamics [39.63609604649394]
  We introduce a classical computational method for quantum dynamics that relies on a global-in-time variational principle.<n>Our scheme computes the entire state trajectory over a finite time window by minimizing a loss function that enforces the Schr"odinger's equation.<n>We showcase the method by simulating global quantum quenches in the paradigmatic Transverse-Field Ising model in both 1D and 2D.
  arXiv  Detail & Related papers  (2024-12-16T13:48:54Z)
• Benchmarking quantum chaos from geometric complexity [0.23436632098950458]
  We consider a new method to study geometric complexity for interacting non-Gaussian quantum mechanical systems.<n>Within some limitations, geometric complexity can indeed be a good indicator of quantum chaos.
  arXiv  Detail & Related papers  (2024-10-24T14:04:58Z)
• Space-time correlations in monitored kinetically constrained discrete-time quantum dynamics [0.0]
  We show a kinetically constrained many-body quantum system that has a natural implementation on Rydberg quantum simulators.<n>Despite featuring an uncorrelated infinite-temperature average stationary state, the dynamics displays coexistence of fast and slow space-time regions.<n>Our work establishes the large deviation framework for discrete-time open quantum many-body systems as a means to characterize complex dynamics and collective phenomena in quantum processors and simulators.
  arXiv  Detail & Related papers  (2024-08-19T10:24:07Z)
• Spread complexity in saddle-dominated scrambling [0.0]
  We study the spread complexity of the thermofield double state within emphintegrable systems that exhibit saddle-dominated scrambling. Applying the Lanczos algorithm, our numerical investigation reveals that the spread complexity in these systems exhibits features reminiscent of emphchaotic systems.
  arXiv  Detail & Related papers  (2023-12-19T20:41:14Z)
• Taming Quantum Time Complexity [45.867051459785976]
  We show how to achieve both exactness and thriftiness in the setting of time complexity. We employ a novel approach to the design of quantum algorithms based on what we call transducers.
  arXiv  Detail & Related papers  (2023-11-27T14:45:19Z)
• Growth of entanglement of generic states under dual-unitary dynamics [77.34726150561087]
  Dual-unitary circuits are a class of locally-interacting quantum many-body systems. In particular, they admit a class of solvable" initial states for which, in the thermodynamic limit, one can access the full non-equilibrium dynamics. We show that in this case the entanglement increment during a time step is sub-maximal for finite times, however, it approaches the maximal value in the infinite-time limit.
  arXiv  Detail & Related papers  (2022-07-29T18:20:09Z)
• Saturation and recurrence of quantum complexity in random local quantum dynamics [5.803309695504831]
  Quantum complexity is a measure of the minimal number of elementary operations required to prepare a given state or unitary channel. Brown and Susskind conjectured that the complexity of a chaotic quantum system grows linearly in time up to times exponential in the system size, saturating at a maximal value, and remaining maximally complex until undergoing recurrences at doubly-exponential times.
  arXiv  Detail & Related papers  (2022-05-19T17:42:31Z)
• Quantum Non-equilibrium Many-Body Spin-Photon Systems [91.3755431537592]
  dissertation concerns the quantum dynamics of strongly-correlated quantum systems in out-of-equilibrium states. Our main results can be summarized in three parts: Signature of Critical Dynamics, Driven Dicke Model as a Test-bed of Ultra-Strong Coupling, and Beyond the Kibble-Zurek Mechanism.
  arXiv  Detail & Related papers  (2020-07-23T19:05:56Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.