Ehud Altman
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View article: Fractional quantum Hall states under density decoherence
Fractional quantum Hall states under density decoherence Open
Fractional quantum Hall states are promising platforms for topological quantum computation due to their capacity to encode quantum information in topologically degenerate ground states and in the fusion space of non-abelian anyons. We inve…
View article: Stabilization of long-range order in low-dimensional nonequilibrium $O(N)$ models
Stabilization of long-range order in low-dimensional nonequilibrium $O(N)$ models Open
It is now well established that the Mermin-Wagner theorem can be circumvented in nonequilibrium systems, allowing for the spontaneous breaking of a continuous symmetry and the emergence of long-range order in low dimensions. However, only …
View article: Gaplessness from disorder and quantum geometry in gapped superconductors
Gaplessness from disorder and quantum geometry in gapped superconductors Open
It is well known that disorder can induce low-energy Andreev bound states in a sign-changing, but fully gapped, superconductor at $π-$junctions. Generically, these excitations are localized. Starting from a superconductor with a sign-chang…
View article: Linear magnetoresistance from glassy orders
Linear magnetoresistance from glassy orders Open
Several strongly correlated metals display B-linear magnetoresistance (LMR) with a universal slope, in sharp contrast to the scaling predicted by Fermi liquid theory. We provide a unifying explanation of the origin of LMR by focusing o…
View article: Error Threshold of SYK Codes from Strong-to-Weak Parity Symmetry Breaking
Error Threshold of SYK Codes from Strong-to-Weak Parity Symmetry Breaking Open
Quantum error correction (QEC) codes are fundamentally linked to quantum phases of matter: the degenerate ground state manifold corresponds to the code space, while topological excitations represent error syndromes. Building on this concep…
View article: Computational Phase Transitions in Two-Dimensional Antiferromagnetic Melting
Computational Phase Transitions in Two-Dimensional Antiferromagnetic Melting Open
A computational phase transition in a classical or quantum system is a non-analytic change in behavior of an order parameter which can only be observed with the assistance of a nontrivial classical computation. Such phase transitions, and …
View article: Probing Postmeasurement Entanglement without Postselection
Probing Postmeasurement Entanglement without Postselection Open
We study the problem of observing quantum collective phenomena emerging from large numbers of measurements. These phenomena are difficult to observe in conventional experiments because, in order to distinguish the effects of measurement fr…
View article: Diagnostics of Mixed-State Topological Order and Breakdown of Quantum Memory
Diagnostics of Mixed-State Topological Order and Breakdown of Quantum Memory Open
Topological quantum memory can protect information against local errors up to finite error thresholds. Such thresholds are usually determined based on the success of decoding algorithms rather than the intrinsic properties of the mixed sta…
View article: Linear Magnetoresistance from Glassy Orders
Linear Magnetoresistance from Glassy Orders Open
Several strongly correlated metals display B-linear magnetoresistance (LMR) with a universal slope, in sharp contrast to the $B^2$ scaling predicted by Fermi liquid theory. We provide a unifying explanation of the origin of LMR by focusing…
View article: Theory of a Strange Metal in a Quantum Superconductor to Metal Transition
Theory of a Strange Metal in a Quantum Superconductor to Metal Transition Open
Recent experiments with nanopatterned thin films revealed an unusual quantum superconductor to metal phase transition (QSMT) with a linear in temperature resistivity. In contrast, most known examples of such transitions and standard theore…
View article: Finite-Time Teleportation Phase Transition in Random Quantum Circuits
Finite-Time Teleportation Phase Transition in Random Quantum Circuits Open
How long does it take to entangle two distant qubits in a quantum circuit evolved by generic unitary dynamics? We show that if the time evolution is followed by measurements of all but two infinitely separated test qubits, then the entangl…
View article: Scrambling Transition in a Radiative Random Unitary Circuit
Scrambling Transition in a Radiative Random Unitary Circuit Open
We study quantum information scrambling in a random unitary circuit that exchanges qubits with an environment at a rate p. As a result, initially localized quantum information not only spreads within the system, but also spills into the en…
View article: Magnetization amplification in the interlayer pairing superconductor 4Hb-TaS$_2$
Magnetization amplification in the interlayer pairing superconductor 4Hb-TaS$_2$ Open
A recent experiment on the bulk compound 4Hb-TaS$_2$ reveals an unusual time-reversal symmetry-breaking superconducting state that possesses a magnetic memory not manifest in the normal state. Here we provide a mechanism for this observati…
View article: Cross Entropy Benchmark for Measurement-Induced Phase Transitions
Cross Entropy Benchmark for Measurement-Induced Phase Transitions Open
We investigate prospects of employing the linear cross entropy to experimentally access measurement-induced phase transitions without requiring any postselection of quantum trajectories. For two random circuits that are identical in the bu…
View article: Probing post-measurement entanglement without post-selection
Probing post-measurement entanglement without post-selection Open
We study the problem of observing quantum collective phenomena emerging from large numbers of measurements. These phenomena are difficult to observe in conventional experiments because, in order to distinguish the effects of measurement fr…
View article: Measurements Conspire Nonlocally to Restructure Critical Quantum States
Measurements Conspire Nonlocally to Restructure Critical Quantum States Open
We study theoretically how local measurements performed on critical quantum ground states affect long-distance correlations. These states are highly entangled and feature algebraic correlations between local observables. As a consequence, …
View article: Nonlocality and entanglement in measured critical quantum Ising chains
Nonlocality and entanglement in measured critical quantum Ising chains Open
We study the effects of measurements, performed with a finite density in space, on the ground state of the one-dimensional transverse-field Ising model at criticality. Local degrees of freedom in critical states exhibit long-range entangle…
View article: Diagnostics of mixed-state topological order and breakdown of quantum memory
Diagnostics of mixed-state topological order and breakdown of quantum memory Open
Topological quantum memory can protect information against local errors up to finite error thresholds. Such thresholds are usually determined based on the success of decoding algorithms rather than the intrinsic properties of the mixed sta…
View article: Mixed-state topological order and the errorfield double formulation of decoherence-induced transitions
Mixed-state topological order and the errorfield double formulation of decoherence-induced transitions Open
We develop an effective field theory characterizing the impact of decoherence on states with abelian topological order and on their capacity to protect quantum information. The decoherence appears as a temporal defect in the double topolog…
View article: Scrambling Transition in a Radiative Random Unitary Circuit
Scrambling Transition in a Radiative Random Unitary Circuit Open
We study quantum information scrambling in a random unitary circuit that exchanges qubits with an environment at a rate $p$. As a result, initially localized quantum information not only spreads within the system, but also spills into the …
View article: Fractonic Luttinger Liquids and Supersolids in a Constrained Bose-Hubbard Model
Fractonic Luttinger Liquids and Supersolids in a Constrained Bose-Hubbard Model Open
Quantum many-body systems with fracton constraints are widely conjectured to exhibit unconventional low-energy phases of matter. In this work, we demonstrate the existence of a variety of such exotic quantum phases in the ground states of …
View article: Fractonic Luttinger Liquids and Supersolids in a Constrained Bose-Hubbard Model
Fractonic Luttinger Liquids and Supersolids in a Constrained Bose-Hubbard Model Open
This repository contains datasets and simulation code used to create data and figures for the corresponding publication.
View article: Cross Entropy Benchmark for Measurement-Induced Phase Transitions
Cross Entropy Benchmark for Measurement-Induced Phase Transitions Open
We investigate the prospects of employing the linear cross-entropy to experimentally access measurement-induced phase transitions (MIPT) without requiring any postselection of quantum trajectories. For two random circuits that are identica…
View article: Measurement-Induced Power-Law Negativity in an Open Monitored Quantum Circuit
Measurement-Induced Power-Law Negativity in an Open Monitored Quantum Circuit Open
Generic many-body systems coupled to an environment lose their quantum entanglement due to decoherence and evolve to a mixed state with only classical correlations. Here, we show that measurements can stabilize quantum entanglement within …
View article: A universal crossover in quantum circuits governed by a proximate classical error correction transition
A universal crossover in quantum circuits governed by a proximate classical error correction transition Open
We formulate a semi-classical circuit model to clarify the role of quantum entanglement in the recently discovered encoding phase transitions in quantum circuits with measurements. As a starting point we define a random circuit model with …
View article: Measurements conspire nonlocally to restructure critical quantum states
Measurements conspire nonlocally to restructure critical quantum states Open
We study theoretically how local measurements perfomed on critical quantum ground states affect long-distance correlations. These states are highly entangled and feature algebraic correlations between local observables. As a consequence, l…
View article: Solvable theory of a strange metal at the breakdown of a heavy Fermi liquid
Solvable theory of a strange metal at the breakdown of a heavy Fermi liquid Open
We introduce an effective theory for quantum critical points (QCPs) in heavy fermion systems, involving a change in carrier density without symmetry breaking. Our new theory captures a strongly coupled metallic QCP, leading to robust margi…
View article: Absence of Heating in a Uniform Fermi Gas Created by Periodic Driving
Absence of Heating in a Uniform Fermi Gas Created by Periodic Driving Open
Ultracold atomic gas provides a useful tool to explore many-body physics. One of the recent additions to this experimental toolbox is the Floquet engineering, where periodic modulation of the Hamiltonian allows the creation of effective po…