Fermionic Linear Optics (FLO) is a restricted model of quantum computation which in its original form is known to be efficiently classically simulable. We show that, when initialized with suitable input states, FLO circuits can be used to demonstrate quantum computational advantage with strong hardness guarantees. Based on this, we propose a quantum advantage scheme which is a fermionic analogue of Boson Sampling: Fermion Sampling with magic input states.
We consider in parallel two classes of circuits: particle-number conserving (passive) FLO and active FLO that preserves only fermionic parity and is closely related to Matchgate circuits introduced by Valiant. Mathematically, these classes of circuits can be understood as fermionic representations of the Lie groups $U(d)$ and $SO(2d)$. This observation allows us to prove our main technical results. We first show anticoncentration for probabilities in random FLO circuits of both kind. Moreover, we prove robust average-case hardness of computation of probabilities. To achieve this, we adapt the worst-to-average-case reduction based on Cayley transform, introduced recently by Movassagh, to representations of low-dimensional Lie groups. Taken together, these findings provide hardness guarantees comparable to the paradigm of Random Circuit Sampling.
Importantly, our scheme has also a potential for experimental realization. Both passive and active FLO circuits are relevant for quantum chemistry and many-body physics and have been already implemented in proof-of-principle experiments with superconducting qubit architectures. Preparation of the desired quantum input states can be obtained by a simple quantum circuit acting independently on disjoint blocks of four qubits and using 3 entangling gates per block. We also argue that due to the structured nature of FLO circuits, they can be efficiently certified.
Magic states were introduced in the context of Clifford circuits as a resource that elevates classically simulatable computations to quantum universal capability, while maintaining the same gate set. Here we study magic states in the context of matchgate (MG) circuits, where the notion becomes more subtle, as MGs are subject to locality constraints and also the SWAP gate is not available. Nevertheless a similar picture of gate-gadget constructions applies, and we show that every pure fermionic state which is non-Gaussian, i.e. which cannot be generated by MGs from a computational basis state, …
Non-Local Magic Resources for Fermionic Gaussian States
Scuola Superiore Meridionale（南方高等学院）；INFN Sezione di Napoli（那不勒斯国家核物理研究所）；Institut für Theoretische Physik, Universität zu Köln（科隆大学理论物理研究所）；Dipartimento di Fisica e Astronomia, Università di Bologna and INFN, Sezione di Bologna（博洛尼亚大学物理与天文系及博洛尼亚国家核物理研究所）；Dipartimento di Fisica ‘Ettore Pancini’, Università degli Studi di Napoli Federico II（那不勒斯费德里科二世大学“埃托雷·潘奇尼”物理系）
Entanglement spectrum and magic in higher-dimensional free fermionic systems
Universität zu Köln（科隆大学）；Scuola Superiore Meridionale（南方高等学院）；INFN Sezione di Napoli（那不勒斯 INFN 分部）；SISSA（国际高等研究学院）；INFN Sezione di Trieste（的里雅斯特 INFN 分部）
Classical simulation of free-fermionic dynamics and quantum chemistry with magic input
Korea Advanced Institute of Science and Technology（韩国科学技术院）；Center for Theoretical Physics of the Polish Academy of Sciences（波兰科学院理论物理中心）；University of Helsinki（赫尔辛基大学）；HUN-REN Wigner Research Centre for Physics（匈牙利研究与教育网络温格物理学研究中心）；Algorithmiq Ltd（Algorithmiq有限公司）
Efficient Learning of Fermionic Magic States under Free-Fermion Evolution
Graduate School of Quantum Science and Technology, Korea Advanced Institute of Science and Technology（韩国科学技术院量子科学与技术研究生院）；School of Computational Sciences, Korea Advanced Institute of Science and Technology（韩国科学技术院计算科学学院）；Department of Physics, Korea Advanced Institute of Science and Technology（韩国科学技术院物理系）
The University of Hong Kong（香港大学）；HK Institute of Quantum Science & Technology（香港量子科学研究所）；Freie Universität Berlin（柏林自由大学）；Dahlem Center for Complex Quantum Systems, Freie Universität Berlin（柏林自由大学达勒姆复杂量子系统中心）；Helmholtz-Zentrum Berlin für Materialien und Energie（柏林亥姆霍兹材料与能源中心）
Fermionic magic resources in disordered quantum spin chains
Szkoła Doktorska Nauk Ścisłych i Przyrodniczych, Uniwersytet Jagielloński（雅盖隆大学自然科学博士学院）；Instytut Fizyki Teoretycznej, Wydział Fizyki, Astronomii i Informatyki Stosowanej, Uniwersytet Jagielloński（雅盖隆大学物理、天文学与应用信息学系理论物理研究所）；Mark Kac Complex Systems Research Center, Uniwersytet Jagielloński（雅盖隆大学马克·卡克复杂系统研究中心）；Barcelona Supercomputing Center（巴塞罗那超级计算中心）
Pauli spectrum and nonstabilizerness of random fermionic Gaussian states
Universität zu Köln（科隆大学）；Barcelona Supercomputing Center（巴塞罗那超级计算中心）；Technical University of Munich（慕尼黑工业大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与工程中心）
Optimal and improved gate decompositions for accelerated classical simulation of near-Gaussian fermionic circuits
Phasecraft Ltd（Phasecraft有限公司）；Department of Mathematics, School of Computation, Information and Technology, Technical University of Munich（慕尼黑工业大学计算、信息与技术学院数学系）；Munich Center for Quantum Science and Technology（慕尼黑量子科学与技术中心）
Classical simulation of a quantum circuit with noisy magic inputs
Graduate School of Quantum Science and Technology, Korea Advanced Institute of Science and Technology (KAIST)（韩国科学技术院量子科学与技术研究生院）；Department of Physics, Korea Advanced Institute of Science and Technology (KAIST)（韩国科学技术院物理系）
Optical trapping of molecules with long coherence times is crucial for many protocols in quantum information and metrology. However, the factors that limit the lifetimes of the trapped molecules remain elusive and require improved understanding of the underlying molecular structure. Here we show that measurements of vibronic line strengths in weakly and deeply bound $^{88}$Sr$_2$ molecules, combined with \textit{ab initio} calculations, allow for unambiguous identification of vibrational quantum numbers. This, in turn, enables the construction of refined excited potential energy curves that in…
Bosonization in curved spacetime maps massive Thirring model (self-interacting Dirac fermions) to a generalized sine-Gordon model, both living in $1+1$-dimensional curved spacetime. Applying this duality we have shown that the Thirring model fermion, in non-relativistic limit, gets identified with the soliton of non-linear Scrodinger model with Kerr form of non-linearity. We discuss one particular optical soliton in the latter model and relate it with the Thirring model fermion.
Because Majorana zero modes store quantum information non-locally, they are protected from noise, and have been proposed as a building block for a quantum computer. We show how to use the same protection from noise to implement universal fermionic quantum computation. Our architecture requires only two Majoranas to encode a fermionic quantum degree of freedom, compared to alternative implementations which require a minimum of four Majoranas for a spin quantum degree of freedom. The fermionic degrees of freedom support both unitary coupled cluster variational quantum eigensolver and quantum pha…
We demonstrate that the coherence of a single mobile atomic qubit can be well preserved during a transfer process among different optical dipole traps (ODTs). This is a prerequisite step in realizing a large-scale neutral atom quantum information processing platform. A qubit encoded in the hyperfine manifold of $^{87}$Rb atom is dynamically extracted from the static quantum register by an auxiliary moving ODT and reinserted into the static ODT. Previous experiments were limited by decoherences induced by the differential light shifts of qubit states. Here we apply a magic-intensity trapping te…
International School for Advanced Studies (SISSA)（高等高级研究学院）；INFN Sezione di Trieste（的里雅斯特意大利国家核物理研究所）；University of Cambridge（剑桥大学）；Ecole Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）
Collective inhibition of light scattering from atoms into an optical cavity at a magic frequency
HUN-REN Wigner RCP（匈牙利科学院温格研究中心）；Department of Theoretical Physics, University of Szeged（塞格德大学理论物理系）；Department of Physics of Complex Systems, ELTE Eötvös Loránd University（罗兰大学复杂系统物理系）
The emergence of quantum technologies is heating up the debate on quantum supremacy, usually focusing on the feasibility of looking good on paper algorithms in realistic settings, due to the vulnerability of quantum systems to myriad sources of noise. In this vein, an interesting example of quantum pseudo-telepathy games that quantum mechanical resources can theoretically outperform classical resources is the Magic Square game (MSG), in which two players play against a referee. Due to noise, however, the unit winning probability of the players can drop well below the classical limit. Here, we …
Standard Quantum Teleportation of an Arbitrary N-Qubit State, Non-Existence of Magic Basis and Existence of Magic Partial Bases for 2N Entangled Qubit States with N>1
We revisit the phenomenon of the resonant transmission of fermionic carriers through a quantum device connected to two contacts with different chemical potentials. We show that, besides the traditional in solid-state physics Landauer-Büttiker approach, this phenomenon can be also described by the non-Markovian master equation for the reduced density matrix of the fermions in the quantum device. We identify validity regions of both approaches in the system parameter space and argue that for large relaxation rates the accuracy of the latter approach greatly exceeds the accuracy of the former.
We propose to use fermionic atoms with degenerate ground and excited internal levels ($F_g\rightarrow F_e$), loaded into the motional ground state of an optical lattice with two atoms per lattice site, to realize dark states with no radiative decay. The physical mechanism behind the dark states is an interplay of Pauli blocking and multilevel dipolar interactions. The dark states are independent of lattice geometry, can support an extensive number of excitations and can be coherently prepared using a Raman scheme taking advantage of the quantum Zeno effect. These attributes make them appealing…
