Physical Review X最新文献

{"title":"Fast, Robust, and Laser-Free Universal Entangling Gates for Trapped-Ion Quantum Computing","authors":"Markus Nünnerich, Daniel Cohen, Patrick Barthel, Patrick H. Huber, Dorna Niroomand, Alex Retzker, Christof Wunderlich","doi":"10.1103/physrevx.15.021079","DOIUrl":"https://doi.org/10.1103/physrevx.15.021079","url":null,"abstract":"A novel two-qubit entangling gate for trapped-ion quantum processors is proposed theoretically and demonstrated experimentally. During the gate, double-dressed quantum states are created by applying a phase-modulated continuous driving field. The speed of this quantum gate is an order of magnitude higher than that of previously demonstrated rf controlled two-qubit entangling gates in static magnetic field gradients. At the same time, the field driving the gate dynamically decouples the qubits from amplitude and frequency noise, increasing the qubits’ coherence time by 3 orders of magnitude. The gate requires only a single continuous rf field per qubit, making it well suited for scaling a quantum processor to large numbers of qubits. Implementing this entangling gate, we generate the Bell states |</a:mo>Φ</a:mi>+</a:mo></a:msup>⟩</a:mo></a:math> and <f:math xmlns:f=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><f:mo stretchy=\"false\">|</f:mo><f:msup><f:mi mathvariant=\"normal\">Ψ</f:mi><f:mo>+</f:mo></f:msup><f:mo stretchy=\"false\">⟩</f:mo></f:math> in less than or equal to <k:math xmlns:k=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><k:mrow><k:mn>313</k:mn><k:mtext> </k:mtext><k:mtext> </k:mtext><k:mi mathvariant=\"normal\">μ</k:mi><k:mi mathvariant=\"normal\">s</k:mi></k:mrow></k:math> with fidelities up to <o:math xmlns:o=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><o:msubsup><o:mn>98</o:mn><o:mrow><o:mo>−</o:mo><o:mn>3</o:mn></o:mrow><o:mrow><o:mo>+</o:mo><o:mn>2</o:mn></o:mrow></o:msubsup><o:mo>%</o:mo></o:math> in a static magnetic gradient of only <q:math xmlns:q=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><q:mrow><q:mn>19.09</q:mn><q:mtext> </q:mtext><q:mtext> </q:mtext><q:mi mathvariant=\"normal\">T</q:mi><q:mo>/</q:mo><q:mi mathvariant=\"normal\">m</q:mi></q:mrow></q:math>. At higher magnetic field gradients, the entangling gate speed can be further improved to match that of laser-based counterparts. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"100 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144210961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emergent Holographic Forces from Tensor Networks and Criticality","authors":"Rahul Sahay, Mikhail D. Lukin, Jordan Cotler","doi":"10.1103/physrevx.15.021078","DOIUrl":"https://doi.org/10.1103/physrevx.15.021078","url":null,"abstract":"The AdS/CFT correspondence stipulates a duality between conformal field theories and certain theories of quantum gravity in one higher spatial dimension. However, probing this conjecture on contemporary classical or quantum computers is challenging. We formulate an efficiently implementable multiscale entanglement renormalization ansatz model of AdS/CFT, providing a mapping between a (1</a:mn>+</a:mo>1</a:mn></a:mrow></a:math>)-dimensional critical spin system and a (<c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><c:mrow><c:mn>2</c:mn><c:mo>+</c:mo><c:mn>1</c:mn></c:mrow></c:math>)-dimensional bulk theory. Using a combination of numerics and analytics, we show that the bulk theory arising from this optimized tensor network furnishes excitations with attractive interactions. Remarkably, these excitations have one- and two-particle energies matching the predictions for matter coupled to AdS gravity at long distances, thus displaying key features of AdS physics. We show that these potentials arise as a direct consequence of entanglement renormalization and discuss how this approach can be used to efficiently simulate bulk dynamics using realistic quantum devices. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"45 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144210962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quartic Quantum Speedups for Planted Inference","authors":"Alexander Schmidhuber, Ryan O’Donnell, Robin Kothari, Ryan Babbush","doi":"10.1103/physrevx.15.021077","DOIUrl":"https://doi.org/10.1103/physrevx.15.021077","url":null,"abstract":"We describe a quantum algorithm for the Planted Noisy k</a:mi>XOR</a:mi></a:math> Problem (also known as Sparse Learning Parity with Noise) that achieves a nearly (fourth-power) speedup over the best known classical algorithm while using exponentially less space. Our work generalizes and simplifies prior work of Hastings [], by building on his quantum algorithm for the tensor principal component analysis (PCA) problem. We achieve our quantum speedup using a general framework based on the Kikuchi method (recovering the quartic speedup for Tensor PCA), and we anticipate it will yield similar speedups for further planted inference problems. These speedups rely on the fact that planted inference problems naturally instantiate the guided sparse Hamiltonian problem. Since the Planted Noisy <c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><c:mi>k</c:mi><c:mi>XOR</c:mi></c:math> Problem has been used as a component of certain cryptographic constructions, our work suggests that some of these are susceptible to superquadratic quantum attacks. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"51 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144201803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic Evidence of Fermionic Behavior in the Vicinity of One-Ninth Plateau in a Kagome Antiferromagnet","authors":"Guoxin Zheng, Dechen Zhang, Yuan Zhu, Kuan-Wen Chen, Aaron Chan, Kaila Jenkins, Byungmin Kang, Zhenyuan Zeng, Aini Xu, D. Ratkovski, Joanna Blawat, Alimamy F. Bangura, John Singleton, Patrick A. Lee, Shiliang Li, Lu Li","doi":"10.1103/physrevx.15.021076","DOIUrl":"https://doi.org/10.1103/physrevx.15.021076","url":null,"abstract":"The spin-1&lt;/a:mn&gt;/&lt;/a:mo&gt;2&lt;/a:mn&gt;&lt;/a:mrow&gt;&lt;/a:math&gt; kagome Heisenberg antiferromagnets are believed to host exotic quantum entangled states. Recently, the reports of &lt;c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;c:mrow&gt;&lt;c:mn&gt;1&lt;/c:mn&gt;&lt;c:mo&gt;/&lt;/c:mo&gt;&lt;c:mn&gt;9&lt;/c:mn&gt;&lt;/c:mrow&gt;&lt;/c:math&gt; magnetization plateau and magnetic oscillations in a kagome antiferromagnet &lt;e:math xmlns:e=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;e:mrow&gt;&lt;e:mrow&gt;&lt;e:msub&gt;&lt;e:mrow&gt;&lt;e:mi&gt;YCu&lt;/e:mi&gt;&lt;/e:mrow&gt;&lt;e:mrow&gt;&lt;e:mn&gt;3&lt;/e:mn&gt;&lt;/e:mrow&gt;&lt;/e:msub&gt;&lt;/e:mrow&gt;&lt;e:msub&gt;&lt;e:mrow&gt;&lt;e:mo stretchy=\"false\"&gt;(&lt;/e:mo&gt;&lt;e:mrow&gt;&lt;e:mi&gt;OH&lt;/e:mi&gt;&lt;/e:mrow&gt;&lt;e:mo stretchy=\"false\"&gt;)&lt;/e:mo&gt;&lt;/e:mrow&gt;&lt;e:mrow&gt;&lt;e:mn&gt;6&lt;/e:mn&gt;&lt;/e:mrow&gt;&lt;/e:msub&gt;&lt;e:mrow&gt;&lt;e:msub&gt;&lt;e:mrow&gt;&lt;e:mi&gt;Br&lt;/e:mi&gt;&lt;/e:mrow&gt;&lt;e:mrow&gt;&lt;e:mn&gt;2&lt;/e:mn&gt;&lt;/e:mrow&gt;&lt;/e:msub&gt;&lt;/e:mrow&gt;&lt;e:mo stretchy=\"false\"&gt;[&lt;/e:mo&gt;&lt;e:msub&gt;&lt;e:mrow&gt;&lt;e:mtext&gt;Br&lt;/e:mtext&gt;&lt;/e:mrow&gt;&lt;e:mrow&gt;&lt;e:mi&gt;x&lt;/e:mi&gt;&lt;/e:mrow&gt;&lt;/e:msub&gt;&lt;e:msub&gt;&lt;e:mrow&gt;&lt;e:mo stretchy=\"false\"&gt;(&lt;/e:mo&gt;&lt;e:mrow&gt;&lt;e:mi&gt;OH&lt;/e:mi&gt;&lt;/e:mrow&gt;&lt;e:mo stretchy=\"false\"&gt;)&lt;/e:mo&gt;&lt;/e:mrow&gt;&lt;e:mrow&gt;&lt;e:mn&gt;1&lt;/e:mn&gt;&lt;e:mo&gt;−&lt;/e:mo&gt;&lt;e:mi&gt;x&lt;/e:mi&gt;&lt;/e:mrow&gt;&lt;/e:msub&gt;&lt;e:mo stretchy=\"false\"&gt;]&lt;/e:mo&gt;&lt;/e:mrow&gt;&lt;/e:math&gt; (YCOB) have made this material a promising candidate for experimentally realizing quantum spin liquid states. Here, we present measurements of the specific heat &lt;m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;m:msub&gt;&lt;m:mi&gt;C&lt;/m:mi&gt;&lt;m:mi&gt;p&lt;/m:mi&gt;&lt;/m:msub&gt;&lt;/m:math&gt; in YCOB in high magnetic fields (up to 41.5 T) down to 0.46 K, and the &lt;o:math xmlns:o=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;o:mrow&gt;&lt;o:mn&gt;1&lt;/o:mn&gt;&lt;o:mo&gt;/&lt;/o:mo&gt;&lt;o:mn&gt;9&lt;/o:mn&gt;&lt;/o:mrow&gt;&lt;/o:math&gt; plateau feature has been confirmed. Moreover, the temperature dependence of &lt;q:math xmlns:q=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;q:msub&gt;&lt;q:mi&gt;C&lt;/q:mi&gt;&lt;q:mi&gt;p&lt;/q:mi&gt;&lt;/q:msub&gt;&lt;q:mo&gt;/&lt;/q:mo&gt;&lt;q:mi&gt;T&lt;/q:mi&gt;&lt;/q:math&gt; in the vicinity of &lt;s:math xmlns:s=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;s:mrow&gt;&lt;s:mn&gt;1&lt;/s:mn&gt;&lt;s:mo&gt;/&lt;/s:mo&gt;&lt;s:mn&gt;9&lt;/s:mn&gt;&lt;/s:mrow&gt;&lt;/s:math&gt; plateau region can be fitted by a linear in &lt;u:math xmlns:u=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;u:mi&gt;T&lt;/u:mi&gt;&lt;/u:math&gt; term which indicates the presence of a Dirac spectrum, together with a constant term, which indicates a finite density of states contributed by other spinon Fermi surfaces. Surprisingly, the constant term is highly anisotropic in the direction of the magnetic field. Additionally, we observe a double-peak feature near 30 T above the &lt;w:math xmlns:w=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;w:mrow&gt;&lt;w:mn&gt;1&lt;/w:mn&gt;&lt;w:mo&gt;/&lt;/w:mo&gt;&lt;w:mn&gt;9&lt;/w:mn&gt;&lt;/w:mrow&gt;&lt;/w:math&gt; plateau which is another hallmark of fermionic excitations in the specific heat. This combination of gapless behavior and the double-peak structure strongly suggests that the &lt;y:math xmlns:y=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;y:mrow&gt;&lt;y:mn&gt;1&lt;/y:mn&gt;&lt;y:mo&gt;/&lt;/y:mo&gt;&lt;y:mn&gt;9&lt;/y:mn&gt;&lt;/y:mrow&gt;&lt;/y:math&gt; plateau in YCOB is nontri","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"11 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Incommensurate Antiferromagnetism in UTe2 under Pressure","authors":"W. Knafo, T. Thebault, S. Raymond, P. Manuel, D. D. Khalyavin, F. Orlandi, E. Ressouche, K. Beauvois, G. Lapertot, K. Kaneko, D. Aoki, D. Braithwaite, G. Knebel","doi":"10.1103/physrevx.15.021075","DOIUrl":"https://doi.org/10.1103/physrevx.15.021075","url":null,"abstract":"The discovery of multiple superconducting phases in UTe</a:mi></a:mrow>2</a:mn></a:mrow></a:msub></a:mrow></a:math> boosted research on correlated-electron physics. This heavy-fermion paramagnet was rapidly identified as a reference compound to study the interplay between magnetism and unconventional superconductivity with multiple degrees of freedom. The proximity to a ferromagnetic quantum phase transition was initially proposed as a driving force to triplet-pairing superconductivity. However, we find here that long-range incommensurate antiferromagnetic order is established under pressure. The propagation vector <c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><c:msub><c:mi mathvariant=\"bold\">k</c:mi><c:mi mathvariant=\"bold\">m</c:mi></c:msub><c:mo>=</c:mo><c:mo stretchy=\"false\">(</c:mo><c:mn>0.07</c:mn><c:mo>,</c:mo><c:mn>0.33</c:mn><c:mo>,</c:mo><c:mn>1</c:mn><c:mo stretchy=\"false\">)</c:mo></c:math> of the antiferromagnetic phase is close to a wave vector where antiferromagnetic fluctuations have previously been observed at ambient pressure. These elements support that <i:math xmlns:i=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><i:mrow><i:msub><i:mrow><i:mi>UTe</i:mi></i:mrow><i:mrow><i:mn>2</i:mn></i:mrow></i:msub></i:mrow></i:math> is a nearly antiferromagnet at ambient pressure. Our work appeals for theories modeling the evolution of the magnetic interactions and electronic properties, driving a correlated paramagnetic regime at ambient pressure to a long-range antiferromagnetic order under pressure. A deeper understanding of itinerant-<k:math xmlns:k=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><k:mi>f</k:mi></k:math>-electron magnetism in <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><m:mrow><m:msub><m:mrow><m:mi>UTe</m:mi></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msub></m:mrow></m:math> will be a key for describing its unconventional superconducting phases. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"41 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interplay of Nanoscale Strain and Smectic Susceptibility in Kagome Superconductors","authors":"Yidi Wang, Hong Li, Siyu Cheng, He Zhao, Brenden R. Ortiz, Andrea Capa Salinas, Stephen D. Wilson, Ziqiang Wang, Ilija Zeljkovic","doi":"10.1103/physrevx.15.021074","DOIUrl":"https://doi.org/10.1103/physrevx.15.021074","url":null,"abstract":"Exotic quantum solids can host electronic states that spontaneously break rotational symmetry of the electronic structure, such as electronic nematic phases and unidirectional charge density waves (CDWs). When electrons couple to the lattice, uniaxial strain can be used to anchor and control this electronic directionality. Here, we reveal an unusual impact of strain on unidirectional “smectic” CDW orders in kagome superconductors AV</a:mi></a:mrow>3</a:mn></a:msub>Sb</a:mi></a:mrow>5</a:mn></a:msub></a:mrow></a:math> using spectroscopic-imaging scanning tunneling microscopy. We discover local decoupling between the smectic electronic director axis and the direction of anisotropic strain. While the two can generally be aligned along the same direction in regions of a small CDW gap, the tendency for alignment decreases in regions where the CDW gap is the largest. This feature, in turn, suggests nanoscale variations in smectic susceptibility, which we attribute to a combination of local strain and electron correlation strength. Overall, we observe an unusually high decoupling rate between the smectic electronic director of the three-state Potts order and anisotropic strain, revealing weak smectoelastic coupling in the CDW phase of kagome superconductors. This finding is phenomenologically different from the extensively studied nematoelastic coupling in the Ising nematic phase of Ising nematic phase of Fe-based superconductor bulk single crystals, providing a contrasting picture of how strain can control electronic unidirectionality in different families of quantum materials. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"238 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrically Driven Cascaded Photon Emission in a Single Molecule","authors":"Katharina Kaiser, Anna Rosławska, Michelangelo Romeo, Fabrice Scheurer, Tomáš Neuman, Guillaume Schull","doi":"10.1103/physrevx.15.021072","DOIUrl":"https://doi.org/10.1103/physrevx.15.021072","url":null,"abstract":"Controlling electrically stimulated quantum light sources (QLSs) is key for developing integrated and low-scale quantum devices. The underlying mechanisms leading to electrically driven quantum emission, however, are complex, as a large number of electronic states of the system can be involved and, thus, impact the emission dynamics. Here, we use a scanning tunneling microscope to electrically excite a model QLS, namely, a single ZnPc molecule, and disentangle the interplay of charge transfer and excited state formation. The luminescence spectra reveal two lines, associated to the emission of the neutral (exciton) and positively charged (trion) ZnPc, both exhibiting single-photon source behavior. In addition, we find a correlation between the charged and neutral emission, specifically, the signature of a photon cascade in which the radiative decay of the molecular trion is followed by the formation and decay of the exciton. By adjusting the charging vs discharging rate, we show that we can control these emission statistics. This generic strategy is further established by a comprehensive rate equation model comprising a variety of states that mediate excited state formation in the electrically driven single and cascaded photon emission process, revealing the complex internal dynamics of the molecular junction. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"35 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144176975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid Quantum-Classical Stochastic Approach to Dissipative Spin-Boson Models","authors":"Naushad A. Kamar, Mohammad Maghrebi","doi":"10.1103/physrevx.15.021073","DOIUrl":"https://doi.org/10.1103/physrevx.15.021073","url":null,"abstract":"Spin-boson models involving many interacting spins and bosons are ubiquitous in quantum simulation platforms. At the same time, characterizing the dynamics of these quantum systems represents a significant challenge. Here, we consider general spin-boson models where bosons are subject to Markovian dissipation (e.g., due to cavity loss). We present an exact hybrid quantum-classical stochastic approach where the solution of a classical stochastic equation—mimicking the bosonic modes—is input into a quantum stochastic equation for the spins. Furthermore, the spins are effectively decoupled for each stochastic realization, which nevertheless comes at the expense of sampling over unphysical states. In contrast with existing stochastic approaches based on the influence functional formalism, we place no restriction (factorizability or Gaussianity) on the initial state, or the spin-boson coupling (except that it be linear in the bosonic operator). Markovian dissipation, being at the heart of our approach, renders the stochastic equations Markovian even in the strong coupling regime. Furthermore, it ensures hermiticity (though not positivity) of the density matrix for each realization, thus improving the convergence of stochastic sampling. Interestingly, we find a condition on the classical simulability of the system based solely on the single atom cooperativity even in a many-body setting. We benchmark and showcase the utility of our approach in several examples, specifically in cases where a direct numerical computation is unfeasible. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"49 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Universal Quantum Dynamics of Bose Polarons","authors":"Jiří Etrych, Gevorg Martirosyan, Alec Cao, Christopher J. Ho, Zoran Hadzibabic, Christoph Eigen","doi":"10.1103/physrevx.15.021070","DOIUrl":"https://doi.org/10.1103/physrevx.15.021070","url":null,"abstract":"Predicting the emergent properties of impurities immersed in a quantum bath is a fundamental challenge that can defy quasiparticle treatments. Here, we measure the spectral properties and real-time dynamics of mobile impurities injected into a weakly interacting homogeneous Bose-Einstein condensate, using two broad Feshbach resonances to tune both the impurity-bath and intrabath interactions. For attractive impurity-bath interactions, the impurity spectrum features a single branch, which away from the resonance corresponds to a well-defined attractive polaron; near the resonance, we observe dramatic broadening of this branch, suggesting a breakdown of the quasiparticle picture. For repulsive impurity-bath interactions, the spectrum features two branches: the attractive branch that is dominated by excitations with energy close to that of the Feshbach dimer, but has a many-body character, and the repulsive polaron branch. Our measurements show that the behavior of impurities in weakly interacting baths is remarkably universal, controlled only by the bath density and a single dimensionless interaction parameter. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"49 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144165231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward an Ab Initio Theory of High-Temperature Superconductors: A Study of Multilayer Cuprates","authors":"Benjamin Bacq-Labreuil, Benjamin Lacasse, A.-M. S. Tremblay, David Sénéchal, Kristjan Haule","doi":"10.1103/physrevx.15.021071","DOIUrl":"https://doi.org/10.1103/physrevx.15.021071","url":null,"abstract":"Significant progress toward a theory of high-temperature superconductivity in cuprates has been achieved via the study of effective one- and three-band Hubbard models. Nevertheless, material-specific predictions, while essential for constructing a comprehensive theory, remain challenging due to the complex relationship between real materials and the parameters of the effective models. By combining cluster dynamical mean-field theory and density functional theory in a charge-self-consistent manner, here we show that the goal of material-specific predictions for high-temperature superconductors from first principles is within reach. To demonstrate the capabilities of our approach, we take on the challenge of explaining the remarkable physics of multilayer cuprates by focusing on the two representative Ca&lt;/a:mi&gt;&lt;/a:mrow&gt;(&lt;/a:mo&gt;1&lt;/a:mn&gt;+&lt;/a:mo&gt;n&lt;/a:mi&gt;)&lt;/a:mo&gt;&lt;/a:mrow&gt;&lt;/a:msub&gt;Cu&lt;/a:mi&gt;&lt;/a:mrow&gt;n&lt;/a:mi&gt;&lt;/a:mrow&gt;&lt;/a:msub&gt;&lt;/a:mrow&gt;O&lt;/a:mi&gt;&lt;/a:mrow&gt;2&lt;/a:mn&gt;n&lt;/a:mi&gt;&lt;/a:mrow&gt;&lt;/a:msub&gt;Cl&lt;/a:mi&gt;&lt;/a:mrow&gt;2&lt;/a:mn&gt;&lt;/a:mrow&gt;&lt;/a:msub&gt;&lt;/a:mrow&gt;&lt;/a:mrow&gt;&lt;/a:mrow&gt;&lt;/a:math&gt; and &lt;f:math xmlns:f=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;f:mrow&gt;&lt;f:msub&gt;&lt;f:mrow&gt;&lt;f:mi&gt;HgBa&lt;/f:mi&gt;&lt;/f:mrow&gt;&lt;f:mrow&gt;&lt;f:mn&gt;2&lt;/f:mn&gt;&lt;/f:mrow&gt;&lt;/f:msub&gt;&lt;/f:mrow&gt;&lt;f:mrow&gt;&lt;f:msub&gt;&lt;f:mrow&gt;&lt;f:mi&gt;Ca&lt;/f:mi&gt;&lt;/f:mrow&gt;&lt;f:mrow&gt;&lt;f:mo stretchy=\"false\"&gt;(&lt;/f:mo&gt;&lt;f:mi&gt;n&lt;/f:mi&gt;&lt;f:mo&gt;−&lt;/f:mo&gt;&lt;f:mn&gt;1&lt;/f:mn&gt;&lt;f:mo stretchy=\"false\"&gt;)&lt;/f:mo&gt;&lt;/f:mrow&gt;&lt;/f:msub&gt;&lt;f:mrow&gt;&lt;f:msub&gt;&lt;f:mrow&gt;&lt;f:mi&gt;Cu&lt;/f:mi&gt;&lt;/f:mrow&gt;&lt;f:mrow&gt;&lt;f:mi&gt;n&lt;/f:mi&gt;&lt;/f:mrow&gt;&lt;/f:msub&gt;&lt;/f:mrow&gt;&lt;f:mrow&gt;&lt;f:msub&gt;&lt;f:mrow&gt;&lt;f:mi mathvariant=\"normal\"&gt;O&lt;/f:mi&gt;&lt;/f:mrow&gt;&lt;f:mrow&gt;&lt;f:mo stretchy=\"false\"&gt;(&lt;/f:mo&gt;&lt;f:mn&gt;2&lt;/f:mn&gt;&lt;f:mi&gt;n&lt;/f:mi&gt;&lt;f:mo&gt;+&lt;/f:mo&gt;&lt;f:mn&gt;2&lt;/f:mn&gt;&lt;f:mo stretchy=\"false\"&gt;)&lt;/f:mo&gt;&lt;/f:mrow&gt;&lt;/f:msub&gt;&lt;/f:mrow&gt;&lt;/f:mrow&gt;&lt;/f:math&gt; families. We shed light on the microscopic origin of many salient features of multilayer cuprates, in particular, the &lt;m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;m:mi&gt;n&lt;/m:mi&gt;&lt;/m:math&gt; dependence of their superconducting properties. The growth of &lt;o:math xmlns:o=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;o:msub&gt;&lt;o:mi&gt;T&lt;/o:mi&gt;&lt;o:mi&gt;c&lt;/o:mi&gt;&lt;/o:msub&gt;&lt;/o:math&gt; from the single-layer to the trilayer compounds is here explained by the reduction of the charge transfer gap and, consequently, the growth of superexchange &lt;q:math xmlns:q=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;q:mi&gt;J&lt;/q:mi&gt;&lt;/q:math&gt; as &lt;s:math xmlns:s=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;s:mi&gt;n&lt;/s:mi&gt;&lt;/s:math&gt; increases. The origin of both is traced to the appearance of low-energy conduction bands reminiscent of standing wave modes confined within the stack of &lt;u:math xmlns:u=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;u:mrow&gt;&lt;u:msub&gt;&lt;u:mrow&gt;&lt;u:mi&gt;CuO&lt;/u:mi&gt;&lt;/u:mrow&gt;&lt;u:mrow&gt;&lt;u:mn&gt;2&lt;/u:mn&gt;&lt;/u:mrow&gt;&lt;/u:msub&gt;&lt;/u:mrow&gt;&lt;/u:math&gt; planes. We interpret the ultimate drop of &lt;w:math xmlns:w=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"&gt;&lt;w:msub&gt;&lt;w:mi&gt;T&lt;/w:mi&gt;&lt;w:mi&gt;c&lt;/w:mi&gt;&lt;/w:msub&gt;&lt;/w:m","PeriodicalId":20161,"journal":{"name":"Physical Review X","volume":"58 1","pages":""},"PeriodicalIF":12.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144165230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}