Dynamical discontinuities in repeated weak measurements revealed by complex weak values

• URL: http://arxiv.org/abs/2511.03352v1
• Date: Wed, 05 Nov 2025 10:46:02 GMT
• Title: Dynamical discontinuities in repeated weak measurements revealed by complex weak values
• Abstract summary: We investigate discontinuities that arise when the post-selected polar angle is used as a control parameter.<n>No discontinuities occur when the weak value remains real for all post-selection angles.<n>Remarkably, the associated critical exponent is 1, independent of system parameters.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Critical phenomena reveal universal behavior in complex systems, and uncovering analogous effects in quantum weak measurement protocols with post-selection provides new insight into how measurement backaction can shape quantum dynamics. This work investigates dynamical discontinuities that arise when the post-selected polar angle is used as a control parameter. The system evolves under repeated applications of a weak measurement protocol with post-selection, in which the meter state is retained after each iteration while the system is renewed. The emergence of these discontinuities is shown to be determined by the structure of the weak value: when the weak value has a nonzero imaginary component, a discontinuity appears in the expectation value of meter observables precisely at the point where the imaginary part of the weak value vanishes as a function of the post-selection polar angle. In contrast, no discontinuities occur when the weak value remains real for all post-selection angles. The phenomenon originates from the eigenstructure of the protocol's Kraus operator, with the stability of fixed points changing at the critical point where the discontinuity arises. Remarkably, the associated critical exponent is 1, independent of system parameters. These results open new perspectives for engineering non-analytic behavior in measurement-based quantum control and for probing criticality in post-selected quantum dynamics using weak measurements with weak values.

Related papers

• Anomalous weak values in a generalized Mach-Zehnder interferometer extracted directly from intensity measurements [1.2722697496405462]
  We introduce a method to fully characterize path weak-values in a generalized Mach-Zehnder interferometer.<n>We experimentally demonstrate the technique in matter-wave interferometry.
  arXiv  Detail & Related papers  (2026-06-23T16:50:05Z)
• Security in a prepare-and-measure quantum key distribution protocol when the receiver uses weak values to guess the sender's bits [0.0]
  We explore a scenario where the formalism of weak values for mixed states is employed in a quantum communication protocol.<n>We conclude that the weak values may not be elements of the reality of weak measurements, contrary to what the proponents of weak values proposed.
  arXiv  Detail & Related papers  (2025-11-03T13:25:45Z)
• Time Symmetry, Retrocausality, and Emergent Collapse: The Tlalpan Interpretation of Quantum Mechanics [51.56484100374058]
  The Tlalpan Interpretation (QTI) proposes that the wavefunction collapse is not a primitive, axiomatic rule but an emergent phenomenon.<n>The novelty of QTI lies in its embedding of collapse within the conceptual language of critical phenomena in statistical physics.
  arXiv  Detail & Related papers  (2025-08-25T20:30:56Z)
• Theory of free fermions dynamics under partial post-selected monitoring [49.1574468325115]
  We derive a partial post-selected Schrdinger"o equation based on a microscopic description of continuous weak measurement. We show that the passage to the monitored universality occurs abruptly at finite partial post-selection. Our approach establishes a way to study MiPTs for arbitrary subsets of quantum trajectories.
  arXiv  Detail & Related papers  (2023-12-21T16:53:42Z)
• On the relevance of weak measurements in dissipative quantum systems [0.0]
  We show that in systems with non-degenerate eigenstates, weak values always converge to the expectation value of the measured observable. We propose a method for extracting information about the dissipative dynamics of a system using weak values at short dissipation times.
  arXiv  Detail & Related papers  (2023-08-01T14:24:21Z)
• Evolution of many-body systems under ancilla quantum measurements [58.720142291102135]
  We study the concept of implementing quantum measurements by coupling a many-body lattice system to an ancillary degree of freedom. We find evidence of a disentangling-entangling measurement-induced transition as was previously observed in more abstract models.
  arXiv  Detail & Related papers  (2023-03-13T13:06:40Z)
• Universality of critical dynamics with finite entanglement [68.8204255655161]
  We study how low-energy dynamics of quantum systems near criticality are modified by finite entanglement. Our result establishes the precise role played by entanglement in time-dependent critical phenomena.
  arXiv  Detail & Related papers  (2023-01-23T19:23:54Z)
• Entanglement and Absorbing-State Transitions in Interactive Quantum Dynamics [0.027042267806481293]
  Quantum computers motivate the exploration of quantum many-body systems in nontraditional scenarios. We study dynamics in which one attempts to steer the system toward a target state. We argue that the absorbing-state transition generally occurs at different critical parameters from the entanglement transition in individual trajectories.
  arXiv  Detail & Related papers  (2022-11-22T19:00:07Z)
• Driving quantum systems with repeated conditional measurements [0.0]
  We investigate the effect of conditional null measurements on a quantum system and find a rich variety of behaviors. We discuss four generic behaviors that emerge in these monitored systems. When the control parameters are tuned, such that the eigenvalues of the survival operator all coalesce to zero, one has exceptional points that corresponds to situations that violate the null measurement condition.
  arXiv  Detail & Related papers  (2021-04-13T14:21:55Z)
• Robust Control Performance for Open Quantum Systems [0.0]
  A formalism is developed to measure performance based on the transmission of a dynamic perturbation or initial state preparation error. A difficulty arising from the singularity of the closed-loop Bloch equations for the quantum state is overcome by introducing the #-inversion lemma. Additional difficulties occur when symmetry gives rise to multiple open-loop poles, which under symmetry-breaking unfold into single eigenvalues.
  arXiv  Detail & Related papers  (2020-08-31T15:51:22Z)
• Measurement-induced quantum criticality under continuous monitoring [0.0]
  We investigate entanglement phase transitions from volume-law to area-law entanglement in a quantum many-body state under continuous position measurement. We find the signatures of the transitions as peak structures in the mutual information as a function of measurement strength. We propose a possible experimental setup to test the predicted entanglement transition based on the subsystem particle-number fluctuations.
  arXiv  Detail & Related papers  (2020-04-24T19:35:28Z)
• Quantum Zeno effect appears in stages [64.41511459132334]
  In the quantum Zeno effect, quantum measurements can block the coherent oscillation of a two level system by freezing its state to one of the measurement eigenstates. We show that the onset of the Zeno regime is marked by a $textitcascade of transitions$ in the system dynamics as the measurement strength is increased.
  arXiv  Detail & Related papers  (2020-03-23T18:17:36Z)
• Einselection from incompatible decoherence channels [62.997667081978825]
  We analyze an open quantum dynamics inspired by CQED experiments with two non-commuting Lindblad operators. We show that Fock states remain the most robust states to decoherence up to a critical coupling.
  arXiv  Detail & Related papers  (2020-01-29T14:15:19Z)

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.