Sarang Gopalakrishnan
YOU?
Author Swipe
View article: Superdiffusive Transport in Chaotic Quantum Systems with Nodal Interactions
Superdiffusive Transport in Chaotic Quantum Systems with Nodal Interactions Open
We introduce a class of interacting fermionic quantum models in d dimensions with nodal interactions that exhibit superdiffusive transport. We establish nonperturbatively that the nodal structure of the interactions gives rise to long-live…
View article: Spectral properties and coding transitions of Haar-random quantum codes
Spectral properties and coding transitions of Haar-random quantum codes Open
A quantum error-correcting code with a nonzero error threshold undergoes a mixed-state phase transition when the error rate reaches that threshold. We explore this phase transition for Haar-random quantum codes, in which the logical inform…
View article: Classically Sampling Noisy Quantum Circuits in Quasi-Polynomial Time under Approximate Markovianity
Classically Sampling Noisy Quantum Circuits in Quasi-Polynomial Time under Approximate Markovianity Open
While quantum computing can accomplish tasks that are classically intractable, the presence of noise may destroy this advantage in the absence of fault tolerance. In this work, we present a classical algorithm that runs in $n^{\rm{polylog}…
View article: Long-time divergences in the nonlinear response of gapped one-dimensional many-particle systems
Long-time divergences in the nonlinear response of gapped one-dimensional many-particle systems Open
We consider one dimensional many-particle systems that exhibit kinematically protected single-particle excitations over their ground states. We show that momentum and time-resolved 4-point functions of operators that create such excitation…
View article: Scalable accuracy gains from postselection in quantum error correcting codes
Scalable accuracy gains from postselection in quantum error correcting codes Open
Decoding stabilizer codes such as the surface and toric codes involves evaluating free-energy differences in a disordered statistical mechanics model, in which the randomness comes from the observed pattern of error syndromes. We study the…
View article: A robust phase of continuous transversal gates in quantum stabilizer codes
A robust phase of continuous transversal gates in quantum stabilizer codes Open
A quantum error correcting code protects encoded logical information against errors. Transversal gates are a naturally fault-tolerant way to manipulate logical qubits but cannot be universal themselves. Protocols such as magic state distil…
View article: Stabilizing Non-Abelian Topological Order Against Heralded Noise via Local Lindbladian Dynamics
Stabilizing Non-Abelian Topological Order Against Heralded Noise via Local Lindbladian Dynamics Open
An important open question for the current generation of highly controllable quantum devices is understanding which phases can be realized as stable steady states under local quantum dynamics. In this work, we show how robust steady-state …
View article: High-capacity associative memory in a quantum-optical spin glass
High-capacity associative memory in a quantum-optical spin glass Open
The Hopfield model describes a neural network that stores memories using all-to-all-coupled spins. Memory patterns are recalled under equilibrium dynamics. Storing too many patterns breaks the associative recall process because frustration…
View article: Spacetime duality between sequential and measurement-feedback circuits
Spacetime duality between sequential and measurement-feedback circuits Open
Two prevalent approaches for preparing long-range entangled quantum states are (i) linear-depth sequential unitary (SU) circuits, which apply local unitary gates sequentially, and (ii) constant-depth measurement-feedback (MF) circuits, whi…
View article: Dissipative realization of Kondo models
Dissipative realization of Kondo models Open
The Kondo effect is a prototypical strongly correlated phenomenon, and it is usually discussed in the context of unitary dynamics. Here, we demonstrate that the Kondo effect can be induced through non-linear dissipative channels, without r…
View article: Sharp Page transitions in generic Hamiltonian dynamics
Sharp Page transitions in generic Hamiltonian dynamics Open
National Science Foundation http://dx.doi.org/10.13039/100000001
View article: Emergence of Navier-Stokes Hydrodynamics in Chaotic Quantum Circuits
Emergence of Navier-Stokes Hydrodynamics in Chaotic Quantum Circuits Open
We construct an ensemble of two-dimensional nonintegrable quantum circuits that are chaotic but have a conserved particle current, and thus a finite Drude weight. The long-wavelength hydrodynamics of such systems is given by the incompress…
View article: Charge and Spin Sharpening Transitions on Dynamical Quantum Trees
Charge and Spin Sharpening Transitions on Dynamical Quantum Trees Open
The dynamics of monitored systems can exhibit a measurement-induced phase transition (MIPT) between entangling and disentangling phases, tuned by the measurement rate. When the dynamics obeys a continuous symmetry, the entangling phase fur…
View article: Subexponential decay of local correlations from diffusion-limited dephasing
Subexponential decay of local correlations from diffusion-limited dephasing Open
Chaotic quantum systems at finite energy density are expected to act as their own heat baths, rapidly dephasing local quantum superpositions. We argue that in fact this dephasing is subexponential for chaotic dynamics with conservation law…
View article: Mixed-state learnability transitions in monitored noisy quantum dynamics
Mixed-state learnability transitions in monitored noisy quantum dynamics Open
We consider learnability transitions in monitored quantum systems that undergo noisy evolution, subject to a global strong symmetry -- i.e., in addition to the measuring apparatus, the system can interact with an unobserved environment, bu…
View article: Long-Time Limits of Local Operator Entanglement in Interacting Integrable Models
Long-Time Limits of Local Operator Entanglement in Interacting Integrable Models Open
We explore the long-time behavior of Local Operator Entanglement entropy (LOE) in finite-size interacting integrable systems. For certain operators in the Rule 54 automaton, we prove that the LOE saturates to a value that is at most logari…
View article: Eliminating Surface Oxides of Superconducting Circuits with Noble Metal Encapsulation
Eliminating Surface Oxides of Superconducting Circuits with Noble Metal Encapsulation Open
The lifetime of superconducting qubits is limited by dielectric loss, and a major source of dielectric loss is the native oxide present at the surface of the superconducting metal. Specifically, tantalum-based superconducting qubits have b…
View article: Vortex Motion Induced Losses in Tantalum Resonators
Vortex Motion Induced Losses in Tantalum Resonators Open
Tantalum (Ta) based superconducting circuits have been demonstrated to enable record qubit coherence times and quality factors, motivating a careful study of the microscopic origin of the remaining losses that limit their performance. We h…
View article: Conditional Mutual Information and Information-Theoretic Phases of Decohered Gibbs States
Conditional Mutual Information and Information-Theoretic Phases of Decohered Gibbs States Open
Classical and quantum Markov networks -- including Gibbs states of commuting local Hamiltonians -- are characterized by the vanishing of conditional mutual information (CMI) between spatially separated subsystems. Adding local dissipation …
View article: Sharp Page transitions in generic Hamiltonian dynamics
Sharp Page transitions in generic Hamiltonian dynamics Open
We consider the entanglement dynamics of a subsystem initialized in a pure state at high energy density (corresponding to negative temperature) and coupled to a cold bath. The subsystem's Rényi entropies $S_α$ first rise as the subsystem g…
View article: Generalized Hydrodynamics: A Perspective
Generalized Hydrodynamics: A Perspective Open
Conventional hydrodynamics describes systems with few long-lived excitations. In one dimension, however, many experimentally relevant systems feature a large number of long-lived excitations and conserved quantities even at high temperatur…
View article: Superdiffusive transport in chaotic quantum systems with nodal interactions
Superdiffusive transport in chaotic quantum systems with nodal interactions Open
We introduce a class of interacting fermionic quantum models in $d$ dimensions with nodal interactions that exhibit superdiffusive transport. We establish non-perturbatively that the nodal structure of the interactions gives rise to long-l…
View article: Stable Symmetry-Protected Topological Phases in Systems with Heralded Noise
Stable Symmetry-Protected Topological Phases in Systems with Heralded Noise Open
We present a family of local quantum channels whose steady states exhibit stable mixed-state symmetry-protected topological (SPT) order. Motivated by recent experimental progress on "erasure conversion" techniques that allow one to identif…
View article: Correlations, Spectra and Entanglement Transitions in Ensembles of Matrix Product States
Correlations, Spectra and Entanglement Transitions in Ensembles of Matrix Product States Open
We investigate ensembles of Matrix Product States (MPSs) generated by quantum circuit evolution followed by projection onto MPSs with a fixed bond dimension $χ$. Specifically, we consider ensembles produced by: (i) random sequential unitar…
View article: Diffusion cascade in a model of interacting random walkers
Diffusion cascade in a model of interacting random walkers Open
We consider the relaxation of finite-wavevector density waves in a facilitated classical lattice gas. Linear hydrodynamics predicts that such perturbations should relax exponentially, but nonlinear effects were predicted to cause subexpone…
View article: Non-Gaussian diffusive fluctuations in Dirac fluids
Non-Gaussian diffusive fluctuations in Dirac fluids Open
Dirac fluids—interacting systems obeying particle–hole symmetry and Lorentz invariance—are among the simplest hydrodynamic systems; they have also been studied as effective descriptions of transport in strongly interacting Dirac semimetals…
View article: Variational approach to the dynamics of dissipative quantum impurity models
Variational approach to the dynamics of dissipative quantum impurity models Open
Recent experiments with quantum simulators using ultracold atoms and superconducting qubits have demonstrated the potential of controlled dissipation as a versatile tool for realizing correlated many-body states. However, determining the d…
View article: Thermodynamic limitations on fault-tolerant quantum computing
Thermodynamic limitations on fault-tolerant quantum computing Open
We investigate the thermodynamic limits on scaling fault-tolerant quantum computers due to heating from quantum error correction (QEC). Quantum computers require error correction, which accounts for 99.9% of the qubit demand and generates …
View article: Slow crossover from superdiffusion to diffusion in isotropic spin chains
Slow crossover from superdiffusion to diffusion in isotropic spin chains Open
Finite-temperature spin transport in integrable isotropic spin chains (i.e.,\nspin chains with continuous nonabelian symmetries) is known to be\nsuperdiffusive, with anomalous transport properties displaying remarkable\nrobustness to isotr…