We use the Gross-Neveu model in $2<d<4$ as a simple fermionic example for Weinberg's asymptotic safety scenario: despite being perturbatively nonrenormalizable, defines an interacting quantum field theory valid to arbitrarily high momentum scales owing existence of non-Gaussian fixed point. Using functional renormalization group, we study uv behavior both purely well partially bosonized language. show that is realized at points formulations, universal critical exponents which determine...

Recent nuclear magnetic resonance studies [A. Pustogow et al., Nature 574, 72 (2019)] have challenged the prevalent chiral triplet pairing scenario proposed for Sr_{2}RuO_{4}. To provide guidance from microscopic theory as to which other pair states might be compatible with new data, we perform a detailed theoretical study of spin fluctuation mediated this compound. We map out phase diagram function spin-orbit coupling, interaction parameters, and band structure properties over physically...

Deep Reinforcement Learning (RL) has considerably advanced over the past decade. At same time, state-of-the-art RL algorithms require a large computational budget in terms of training time to converge. Recent work started approach this problem through lens quantum computing, which promises theoretical speed-ups for several traditionally hard tasks. In work, we examine class hybrid quantum-classical that collectively refer as variational deep Q-networks (VQ-DQN). We show VQ-DQN approaches are...

Circuit cutting, the partitioning of quantum circuits into smaller independent fragments, has become a promising avenue for scaling up current quantum-computing experiments. Here, we introduce scheme joint cutting two-qubit rotation gates based on virtual gate-teleportation protocol. With that, significantly lower previous upper bounds sampling overhead and prove optimality scheme. Furthermore, show that no classical communication between circuit partitions is required. For parallel derive...

Few-layer graphene systems come in various stacking orders. Considering tight-binding models for electrons on stacked honeycomb layers, this gives rise to a variety of low-energy band structures near the charge neutrality point. Depending order, these enhance or reduce role electron-electron interactions. Here, we investigate instabilities interacting multilayers with focus trilayers ABA and ABC stackings theoretically by means functional renormalization group. We find different types...

We investigate the quantum many-body instabilities of extended Hubbard model for spinless fermions on honeycomb lattice with repulsive nearest-neighbor and second-nearest-neighbor density-density interactions. Recent exact diagonalization infinite density matrix renormalization group results suggest that a putative topological Mott insulator phase driven by repulsion is suppressed, while other numerically approaches support scenario. In present work, we employ functional (fRG) correlated...

Quantum reinforcement learning is an emerging field at the intersection of quantum computing and machine learning. While we intend to provide a broad overview literature on - our interpretation this term will be clarified below put particular emphasis recent developments. With focus already available noisy intermediate-scale devices, these include variational circuits acting as function approximators in otherwise classical setting. In addition, survey algorithms based future fault-tolerant...

Magnetic catalysis describes the enhancement of symmetry-breaking quantum fluctuations in chirally symmetric field theories by coupling fermionic degrees freedom to a magnetic background configuration. We use functional renormalization group investigate this phenomenon for interacting Dirac fermions propagating (2 $+$ 1)-dimensional space-time, described Gross-Neveu model. identify pointlike operators up quartic terms that can be generated flow presence an external field. employ beta...

Circuit cutting, the decomposition of a quantum circuit into independent partitions, has become promising avenue towards experiments with larger circuits in noisy-intermediate scale (NISQ) era. While previous work focused on cutting qubit wires or two-qubit gates, this we introduce method for multi-controlled Z gates. We construct and prove upper bound <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow class="MJX-TeXAtom-ORD"><mml:mi class="MJX-tex-caligraphic"...

Benchmarking and establishing proper statistical validation metrics for reinforcement learning (RL) remain ongoing challenges, where no consensus has been established yet. The emergence of quantum computing its potential applications in (QRL) further complicate benchmarking efforts. To enable valid performance comparisons to streamline current research this area, we propose a novel methodology, which is based on estimator sample complexity definition outperformance. Furthermore, considering...

Despite the continuous advancements in size and robustness of real quantum devices, reliable large-scale computers are not yet available. Hence, classical simulation algorithms remains crucial for testing new methods estimating advantage. Pushing to their limit is essential, particularly due inherent exponential complexity. Besides established Schr\"odinger-style full statevector simulation, so-called Hybrid Schr\"odinger-Feynman (HSF) approaches have shown promise make simulations more...

We offer an explanation for the recently observed pressure-induced magnetic state in iron-chalcogenide FeSe based on \textit{ab initio} estimates pressure evolution of most important Coulomb interaction parameters. find that increase leads to overall decrease mostly nearest-neighbor repulsion, which turn a reduction nematic order and generation stripe order. treat concomitant effects band renormalization induced interplay self-consistent way determine generic topology temperature-pressure...

We study the quantum many-body instabilities of t−JK−JH Kitaev-Heisenberg Hamiltonian on honeycomb lattice as a minimal model for doped spin-orbit Mott insulator. This spin-1/2 is believed to describe magnetic properties layered transition-metal oxide Na2IrO3. determine ground state system with finite charge-carrier density from functional renormalization group (fRG) correlated fermionic systems. To this end, we derive fRG flow equations adapted lack full spin-rotational invariance in...

Understanding magnetic interactions in the parent compounds of high-temperature superconductors forms basis for determining their role mechanism superconductivity. For iron pnictide such as $A$Fe$_2$As$_2$ ($A=$ Ba, Ca, Sr), although spin excitations have been mapped out throughout entire Brillouin zone (BZ), measurements were carried on twinned samples and did not allow a conclusive determination dynamics. Here we use inelastic neutron scattering to completely map $\sim$100\% detwinned...

Variational quantum algorithms (VQAs) have attracted a lot of attention from the computing community for last few years. Their hybrid quantum-classical nature with relatively shallow circuits makes them promising platform demonstrating capabilities noisy intermediate scale (NISQ) devices. Although classical machine learning focuses on gradient-based parameter optimization, finding near-exact gradients variational (VQCs) parameter-shift rule introduces large sampling overhead. Therefore,...

We elucidate the pivotal role of bandstructure's orbital content in deciding type commensurate magnetic order stabilized within itinerant scenario iron-pnictides. Recent experimental findings tetragonal phase attest to existence so-called charge and spin ordered density wave over spin-vortex crystal phase, latter which tends be favored simplified band models magnetism. Here we show that employing a multiorbital Landau approach based on realistic bandstructures can account for experimentally...

Interacting fermions on the half-filled honeycomb lattice with short-range repulsions have been suggested to host a variety of interesting many-body ground states, e.g., topological Mott insulator. A number recent studies spinless case in terms exact diagonalization, infinite density matrix renormalization group and functional group, however, indicate suppression insulating phase whole range interaction parameters. Here, we complement previous by investigating quantum instabilities...

Quantum computing is a promising technology to address combinatorial optimization problems, for example via the quantum approximate algorithm (QAOA). Its potential, however, hinges on scaling toy problems sizes relevant industry. In this study, we challenge by an elaborate combination of two decomposition methods, namely graph shrinking and circuit cutting. Graph reduces problem size before encoding into QAOA circuits, while cutting decomposes circuits fragments execution medium-scale...

We study the collective magnetic excitations of recently discovered ${C}_{4}$-symmetric spin-density-wave states iron-based superconductors with particular emphasis on their orbital character based an itinerant multiorbital approach. This is important since exist only at moderate interaction strengths where damping effects from a coupling to continuum particle-hole strongly modify shape excitation spectra compared predictions local moment picture. uncover distinct polarization inherent in...

We determine theoretically the effect of spin-orbit coupling on magnetic excitation spectrum itinerant multiorbital systems, with specific application to iron-based superconductors. Our microscopic model includes a realistic ten-band kinetic Hamiltonian, atomic coupling, and Hubbard interactions. results highlight remarkable variability resulting anisotropy despite constant coupling. At same time, exhibits robust universal behavior upon changes in band structure corresponding different...

We study superconducting pairing in the doped Kitaev-Heisenberg model by taking into account recently proposed symmetric off-diagonal exchange $\mathrm{\ensuremath{\Gamma}}$. By performing a mean-field analysis, we classify all possible phases terms of symmetry, explicitly effects spin-orbit coupling. Solving resulting gap equations self-consistently, map out phase diagram that involves several topologically nontrivial states. For $\mathrm{\ensuremath{\Gamma}}<0$, find competition between...

An intriguingly complex phase diagram of Na-doped SrFe2As2 is uncovered using high-resolution thermal-expansion, magnetization and heat-capacity measurements. The detailed temperature dependence the orthorhombic distortion anisotropy uniform magnetic susceptibility provide evidence for nine distinct electronic phases near transition region between stripe antiferromagnetism unconventional superconductivity. In particular, we report finding a new which competes surprisingly strongly with From...

We analyze the magnetic field and gate voltage dependence of longitudinal resistance in an integer quantum Hall Fabry-Pérot interferometer, taking into account interactions between interfering edge mode, a non-interfering mode bulk.For weak bulk-edge coupling sufficiently strong inter-edge interaction, we obtain that interferometer operates Aharonov-Bohm regime with flux periodicity halved respect to usual expectation.Even coupling, this behavior can be observed as subperiodicity...

The data representation in a machine-learning model strongly influences its performance. This becomes even more important for quantum machine learning models implemented on noisy intermediate scale (NISQ) devices. Encoding high dimensional into circuit NISQ device without any loss of information is not trivial and brings lot challenges. While simple encoding schemes (like single qubit rotational gates to encode data) often lead within the circuit, complex with entanglement re-uploading an...

Circuit cutting, the decomposition of a quantum circuit into independent partitions, has become promising avenue towards experiments with larger circuits in noisy-intermediate scale (NISQ) era. While previous work focused on cutting qubit wires or two-qubit gates, this we introduce method for multi-controlled Z gates. We construct and prove upper bound $\mathcal{O}(6^{2K})$ associated sampling overhead, where $K$ is number cuts circuit. This control qubits but can be further reduced to...