Exact cancellation of quantum amplitudes in multiphoton interferences with Fock states at input, the so-called suppression or zero transmission laws generalizing the Hong-Ou-Mandel dip, are useful tool in quantum information and computation. It was recently suggested that all bosonic suppression laws follow from a common permutation symmetry in the input quantum state and the unitary matrix of interferometer. By using the recurrence relations for interference of Fock states, we find a wealth of suppression laws on the beamsplitter and tritter which are not explained by the permutation symmetry principle. Our results reveal that in interference with Fock states on unitary multiports there are whole families of suppression laws for arbitrary total number of bosons even on asymmetric unitary multiports, beyond the previously formulated permutation symmetry principle.
We investigate cat codes that can correct multiple excitation losses and identify two types of logical errors: bit-flip errors due to excessive excitation loss and dephasing errors due to quantum back-action from the environment. We show that selected choices of logical subspace and coherent amplitude can efficiently reduce dephasing errors. The trade-off between the two major errors enables optimized performance of cat codes in terms of minimized decoherence. With high coupling efficiency, we show that one-way quantum repeaters with cat codes feature drastically boosted secure communication r…
Quantum error correction beyond $SU(2)$: spin, bosonic, and permutation-invariant codes from convex geometry
University of Maryland, College Park（马里兰大学帕克分校）；Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park（美国国家标准与技术研究院/马里兰大学联合量子信息与计算科学中心）
Suppression and enhancement of bosonic stimulation by atomic interactions
Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）；Research Laboratory of Electronics, MIT-Harvard Center for Ultracold Atoms, Department of Physics, Massachusetts Institute of Technology（麻省理工学院物理系电子研究实验室、MIT-哈佛超冷原子中心）
We explore the multiparticle transition probabilities in Gaussian unitaries effected by a two-mode Bogoliubov bosonic transformation on the mode annihilation and creation operators. We show that the transition probabilities can be characterized by remarkably simple, yet unsuspected recurrence equations involving a linear combination of probabilities. The recurrence exhibits an interferometric suppression term - a negative probability - which generalizes the seminal Hong-Ou-Mandel effect to more than two indistinguishable photons impinging on a beam splitter of rational transmittance. Unexpecte…
We consider an ensemble of indistinguishable quantum machines and show that quantum statistical effects can give rise to a genuine quantum enhancement of the collective thermodynamic performance. When multiple indistinguishable bosonic work resources are coupled to an external system, the internal energy change of the external system exhibits an enhancement arising from permutation symmetry in the ensemble, which is absent when the latter consists of distinguishable work resources.
The no-knowledge quantum feedback was proposed by Szigeti et al., Phys. Rev. Lett. 113, 020407 (2014), as a measurement-based feedback protocol for decoherence suppression for an open quantum system. By continuously measuring environmental noises and feeding back controls on the system, the protocol can completely reverse the measurement backaction and therefore suppress the system's decoherence. However, the complete decoherence cancellation was shown only for the instantaneous feedback, which is impractical in real experiments. Therefore, in this work, we generalize the original work and inv…
A unified diagrammatic approach to quantum transport in few-level junctions for bosonic and fermionic reservoirs: Application to the quantum Rabi model
Error Mitigation in Bosonic Systems via Virtual Distillation
Chalmers University of Technology（查尔姆斯理工大学）；École polytechnique, Institut Polytechnique de Paris（巴黎综合理工学院，巴黎理工学院）；Université libre de Bruxelles（布鲁塞尔自由大学）；International Iberian Nanotechnology Laboratory (INL)（国际伊比利亚纳米技术实验室）；University of Minho（米尼奥大学）
Quantum theory stipulates that if two particles are identical in all physical aspects, the allowed states of the system are either symmetric or antisymmetric with respect to permutations of the particle labels. Experimentally, the symmetry of the states can be inferred indirectly from the fact that neglecting the correct exchange symmetry in the theoretical analysis leads to dramatic discrepancies with the observations. The only way to directly unveil the symmetry of the states for, say, two identical particles is through the interference of the original state and the physically permuted one, …
Joint Center for Quantum Information and Computer Science (QuICS), UMD/NIST（量子信息与计算联合中心）；Institute for Systems Research, University of Maryland, College Park（马里兰大学学院公园分校系统研究所）；Department of ECE, University of Maryland, College Park（马里兰大学学院公园分校电子与计算机工程系）
Time-delay signature (TDS) suppression of semiconductor lasers with external optical feedback is necessary to ensure the security of chaos-based secure communications. Here we numerically and experimentally demonstrate a technique to effectively suppress the TDS of chaotic lasers using quantum noise. The TDS and dynamical complexity are quantified using the autocorrelation function and normalized permutation entropy at the feedback delay time, respectively. Quantum noise from quadrature fluctuations of vacuum state is prepared through balanced homodyne measurement. The effects of strength and …
The uncanny ability of multiple particles to interfere with one another is one of the core principles of quantum mechanics, and serves as foundation for quantum information processing. In particular, the interplay of constructive and destructive interference with the characteristic exchange statistics of indistinguishable particles give rise to the Hong-Ou-Mandel (HOM) effect, where the bunching of bosons can lead to a perfect suppression of two-particle coincidences between the output ports of a balanced beam splitter. Conversely, in the case of two fermions, anti-bunching can systematically …
Gaussian states, operations, and measurements are central building blocks for continuous-variable quantum information processing which paves the way for abundant applications, especially including network-based quantum computation and communication. To make the most use of the Gaussian processes, it is required to understand and utilize suitable mathematical tools such as the symplectic space, symplectic algebra, and Wigner representation. Applying these mathematical tools to practical quantum scenarios, we developed various schemes for quantum transduction, interference-based bosonic mode per…
To build a universal quantum computer from fragile physical qubits, effective implementation of quantum error correction (QEC) is an essential requirement and a central challenge. Existing demonstrations of QEC are based on a schedule of discrete error syndrome measurements and adaptive recovery operations. These active routines are hardware intensive, prone to introducing and propagating errors, and expected to consume a vast majority of the processing power in a large-scale quantum computer. In principle, QEC can be realized autonomously and continuously by tailoring dissipation within the q…
Instantaneous Sobolev Regularization for Dissipative Bosonic Dynamics
Technical University of Munich（慕尼黑工业大学）；Munich Center for Quantum Science and Technology（慕尼黑量子科学与技术中心）；University of Cambridge（剑桥大学）；Department of Mathematics, University of Tübingen（蒂宾根大学数学系）
Symmetric and Antisymmetric Quantum States from Graph Structure and Orientation
Department of Physics, Federal University of Paran\'a, P.O. Box 19044, Curitiba 81531-980, Paran\'a, Brazil；Department of Mathematics, Federal University of Paran\'a, P.O. Box 19081, Curitiba 81531-980, Paran\'a, Brazil
Open quantum many body systems describe a number of experimental platforms relevant for quantum simulations, ranging from arrays of superconducting circuits to ultracold atoms in optical lattices. Their theoretical understanding is hampered by their large Hilbert space and by their intrinsic nonequilibrium nature, limiting the applicability of many traditional approaches. In this work we extend the nonequilibrium bosonic Dynamical Mean Field Theory (DMFT) to Markovian open quantum systems. Within DMFT, a Lindblad master equation describing a lattice of dissipative bosonic particles is mapped o…
