Controlled Interaction Quenching

Updated 9 November 2025

Controlled quenching of interactions is the deliberate, protocol-based tuning of interparticle forces to drive non-equilibrium dynamics and emergent states.
It employs rapid changes in parameters such as pulse duration, field orientation, or Feshbach resonance to suppress classical behaviors and stabilize metastable regimes.
Applications span quantum optics, ultracold atoms, spintronics, and soft matter, offering versatile tools for state preparation, diagnostics, and phase engineering.

Controlled quenching of interactions refers to the deliberate, protocol-based tuning—usually abrupt or rapid—of the strengths, types, or effective forms of interparticle, interspin, or interaction Hamiltonians in many-body systems. This approach enables non-equilibrium control of relaxation pathways, dynamical freezing, metastability, and emergent order, often with no analog in equilibrium thermodynamics or classical physics. Across condensed matter, ultracold atoms, spintronics, quantum optics, and soft matter, controlled interaction quenching functions as a universal paradigm to steer, suppress, or stabilize new dynamical and structural states.

1. Quantum Quenching of Radiation Reaction in Intense Laser Pulses

The quantum quenching of radiation losses describes the regime in which the expected continuous energy dissipation due to radiation reaction (RR) can be suppressed or “switched off” by engineering the spatiotemporal properties of the fields, such that the probability $P_0$ of no hard-photon emission becomes non-negligible. In strongly relativistic conditions ( $a_0 \gg 1$ , with $a_0$ the normalized vector potential of the electromagnetic pulse), photon emission becomes stochastic and discrete, governed by the instantaneous quantum parameter $\chi_e$ . For ultra-short pulses, the key figure of merit is the integrated emission probability per electron: $P_1 \approx 0.0493\,a_0\,N,$ where $N$ is the number of optical cycles. The threshold for observable quenching is $P_1 \lesssim 1$ , yielding

$N \lesssim 20.3/a_0, \quad \text{or in pulse duration} \quad \tau/T \lesssim 47/a_0,$

with $T=2\pi/\omega$ . For $a_0=200$ , quenching occurs for $\tau/T \lesssim 0.24$ , i.e., sub-cycle pulses.

In QED, the probability of zero emissions is $P_0 = \exp(-P_1)$ ; for $P_1 \lesssim 1$ , $P_0$ remains significant, allowing a measurable fraction of electrons to traverse the pulse without energy loss. By contrast, in classical Landau–Lifshitz theory, RR is continuous and deterministic: all electrons lose energy, precluding quenching by any pulse-shaping protocol.

Experimental schemes exploit this by measuring electron trajectories after the pulse: electrons that experience no recoil populate a classically forbidden region. Current laser facilities ( $a_0 \sim 50$ , $\tau \sim 4$ –$8$ cycles) can resolve this phenomena at the percent level. Controlled quenching thus establishes a strict quantum-classical boundary in RR and suggests protocols both for controlling electron acceleration and for direct diagnostics of ultrashort laser pulse structure.

2. Selective Freezing and Effective Hamiltonian Engineering in Artificial Spin Systems

Controlled quenching is central to the preparation of metastable or nonthermal artificial spin states, such as in one-dimensional artificial kagomé chains comprised of dipolar-coupled nanomagnets. Under slow ac demagnetization—with a field ramped from $\pm 250$ mT to zero over $\sim 80$ h and sample rotation at $\sim 10$ Hz—spins with lower coordination (“dangling ribs”) remain dynamically active longer than “backbone” (spine) spins.

During this protocol, flux-closure loops dominate locally, imposing antiferromagnetic alignment on spine third-neighbor pairs. The result is an effective quenching (kinetic suppression) of these couplings: the standard dipolar Hamiltonian

$H = \sum_{n=1}^6 J_n \sum_{\langle i,j \rangle_n} \sigma_i \sigma_j$

is replaced by

$H_{\rm eff} = ... + J_3' \sum_{\langle i,j \rangle_{3'}} \sigma_i \sigma_j + J_3'' \sum_{\langle i,j \rangle_{3''}} \sigma_i \sigma_j + ...,$

with $J_3''\approx0$ for spine-spine pairs, $J_3'\approx J_3$ elsewhere. This selective freezing can be extended: in higher dimensions, edge or backbone bonds can be dynamically quenched via geometry- and protocol-tailored demagnetization sequences. This technique enables the realization of effective Hamiltonians featuring programmatically turned-off interactions, directly facilitating the paper of exotic ordered, metastable, or glassy spin textures (Salmon et al., 2023).

3. Dynamical Soliton Generation via Interaction Quenches in Quantum Gases

Controlling inter-component interactions in ultracold atomic mixtures—typically through Feshbach resonance tuning—enables the dynamical formation of solitary wave complexes upon crossing miscibility thresholds. In 1D Bose-Bose mixtures (e.g., $^{87}$ Rb in different hyperfine states), the interspecies interaction $g_{AB}$ is abruptly quenched across the boundary $g_{AB}^2=g_{AA}g_{BB}$ . The system's response depends on the direction of the quench:

Miscible $\to$ Immiscible: Density modulation develops, generating filaments corresponding to dark-bright solitons—localized notches in one component filled by the other. Their number scales as $N_{\rm DB}\sim\sqrt{N_A}$ or $\sqrt{g^f_{AB}-g_{AB}^{\rm(th)}}$ , saturating when cloud sizes are fixed.
Immiscible $\to$ Miscible: Counterflow and interference produce trains of dark-antidark solitons, with their number depending linearly on the component populations and the depth below threshold.

Trap geometry and particle imbalance tune these outcomes. The methodology provides a blueprint for deterministic creation of vector soliton trains in quasi-1D atomic gases, with empirical scaling relations for soliton numbers and breathing-mode frequencies (Kiehn et al., 2019).

4. Control of Prethermalization and Thermalization Pathways by Interaction Quenching

In interacting quantum chains or multi-component Fermi gases, controlled quenching of interaction strengths and symmetries manipulates the pathway from integrable (prethermal) to thermalizing dynamics.

Tuneable Integrability-Breaking: In Peierls-dimerized fermion chains, post-quench interaction $U$ determines the lifetime $\tau_0(U)$ of prethermal plateaux and the relaxation form—controlled via a deformed generalized Gibbs ensemble (GGE). For $U\ll J$ , the quasi-conserved quantities $\mathcal{Q}_\alpha(k)$ (mode occupations dressed to $O(U)$ ) yield a prethermal regime absent full thermalization over simulation times.
Multicomponent Fermi Gases: For $N \ge 4$ species, a quantum quench that breaks SU $(N)$ symmetry (e.g., switching on spin-changing interactions $\delta g\ne0$ ) suppresses prethermal plateaux if initial populations are imbalanced. For $N=2$ , or for density imbalances blocking all spin-changing processes, prethermal states remain robust, setting a protocol for isolation or rapid approach to ergodicity (Essler et al., 2013, Huang et al., 2019).

Thus, interaction quenching—by amplitude and via symmetry-breaking channels—acts as a control knob for the emergence and suppression of nonthermal transient regimes, with the initial state's phase space crucial to the outcome.

5. Controlled Quenching in Long-Range, Glassy, and Metastable Systems

Rapid interaction or thermal quenches across phase transitions or competing-order landscapes are a powerful route to freezing, shielding, or trapping the dynamical evolution—phenomena that broadly generalize to classical and quantum many-body systems.

Thermally Quenched Metastable Order: In frustrated Ising models with competing interactions, rapid cooling ( $dT/dt \gg R_c$ ) kinetically arrests the system in a fine mosaic of competing domains, due to large barriers for domain-wall elimination. The degree of disorder, life-time of the trapped phase, and critical trapping rate are fully parameterized by the interaction strengths and Arrhenius activation energy for local flips. This mechanism underpins the formation of glass-like states in artificial electron-lattice models, metallic glasses, and other systems with multiple ordering tendencies (Oike et al., 24 Apr 2025).
Long-Range Interactions and Cooperative Shielding: In long-range-interacting Fermi-Hubbard or Hamiltonian Mean-Field (HMF) models, sudden global quenches may result in “freezing” (non-ergodic preservation of low-energy distributions) if spectral gaps are large (for exponent $\alpha<d$ ), and “shielding” (bulk dynamics decoupled from long-range features) in the presence of disorder-induced semicircular density of states. Both regimes are interpreted as quantum analogues of quasi-stationary states (QSSs) whose lifetimes diverge with system size (Arrufat-Vicente et al., 8 Jul 2024, Gupta et al., 2016).
Protocol-Driven Cooling and Texture Selection: In both optical-cavity atomic systems and ferroic materials, iterative quench–filtering, or rapid cooling through phase competition landscapes, steers the system into atypical or hidden domain patterns not attainable by equilibrium methods. Real-time domain imaging in orthoferrites demonstrates selection between stripe, maze, or hybrid ferroic domain states by tuning quench rates; kinetic fragmentation and slow relaxation timescales are described via a Landau-Ginzburg functional with competing order parameters and biquadratic couplings (Horstmann et al., 23 Dec 2024).

6. Interaction Quenching in Molecular Collisions and Spin Transport

The orientation or symmetry of interaction channels can be dynamically controlled to tune specific inelastic rates:

Rotational Quenching in Cold Collisions: The cross section for rotational quenching in HD+H $_2$ can be maximized by aligning the HD molecule with the collision axis or minimized by aligning at the “magic angle,” i.e., the zero of $P_2(\cos\beta)$ . Helicity-based selection rules dictate that the $m=0$ channel dominates at $\beta=0$ ; suppression of helicity-conserving transitions at the magic angle leads to a quenching-rate ratio up to 6. This geometric control generalizes to molecules with higher $j$ and enables state-resolved selection of reaction pathways (Croft et al., 2019).
Hidden Dzyaloshinskii-Moriya Interactions and Spin Quenching: In uniaxial antiferromagnets with globally inversion-symmetric but locally hidden Dzyaloshinskii–Moriya terms, the magnon’s spin angular momentum along the Néel axis is strictly quenched except at crystallographic degeneracy (nodal) points. A longitudinal field broadens these hot spots, enabling bulk spin transport with field and temperature scaling directly linked to the size of the unquenched phase space. The quenching effect is thus tunable via external fields and symmetry breaking (Ye et al., 9 Oct 2024).

Summary Table: Mechanisms and Outcomes of Controlled Interaction Quenching

System Type	Control Parameter(s)	Outcome/Utility
Relativistic electrons in lasers	Pulse duration $a_0, \tau$	Quantum quenching of RR (Harvey et al., 2016)
Artificial kagomé spin chains	Demagnetization protocol	Selective freezing of couplings (Salmon et al., 2023)
Bose-Bose mixtures (quasi-1D)	$g_{AB}(t)$ via Feshbach	Generation of soliton trains (Kiehn et al., 2019)
Fermi chains, alkali gases	$U$ , $\delta g$ , $N$	Prethermalization control (Essler et al., 2013, Huang et al., 2019)
Ising/metastable/glassy systems	Cooling rate $R=dT/dt$	Kinetic trapping, glass state (Oike et al., 24 Apr 2025)
Fermi-Hubbard with long-range	$U$ , hopping exponent	Freezing/shielding, QSS (Arrufat-Vicente et al., 8 Jul 2024)
Cold molecular collisions	Orientation angle $\beta$	Geometric control of quenching (Croft et al., 2019)
Uniaxial antiferromagnets	Field $H_x$	Magnon spin quenching control (Ye et al., 9 Oct 2024)

7. Outlook and General Principles

Controlled interaction quenching underpins a vast array of protocols for non-equilibrium state preparation, phase engineering, and disorder stabilization. The resulting phenomena typically depend sensitively on the interplay between kinetic bottlenecks, symmetry properties, and the available phase space for interaction-induced transitions. Protocol parameters such as the rate and geometry of parameter change, field orientation, and system size or dimensionality serve as effective control knobs. The field continues to diversify: current directions include leveraging quenching for quantum information transfer, “quench spectroscopy” of Hamiltonians, tunable disorder and frustration, and designing nonequilibrium topological textures.

A plausible implication is that as quantum platforms increase in complexity and control granularity, controlled quenching of interactions will become a central design tool in the preparation, manipulation, and fundamental paper of metastable, nonergodic, or functional quantum and classical states.