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Unconventional Rydberg pumping and applications in quantum information processing
摘要： We propose a mechanism of unconventional Rydberg pumping (URP) via simultaneously driving each Rydberg atom by two classical fields with different strengths of Rabi frequencies. This mechanism differs from the general Rydberg blockade or Rydberg antiblockade since it is closely related to the ground states of atoms, i.e., two atoms in the same ground state are stable while two atoms in different ground states are resonantly excited. Furthermore, we find the URP can be employed to simplify some special quantum information processing tasks, such as implementation of a three-qubit controlled-PHASE gate with only a single Rabi oscillation, preparation of two- and three-dimensional steady-state entanglement with two identical atoms, and realization of the autonomous quantum error correction in a Rydberg-atom-cavity system. The feasibility of the above applications is discussed explicitly by the state-of-the-art technology.
关键词： quantum error correction,Rydberg blockade,Unconventional Rydberg pumping,quantum information processing,Rydberg antiblockade,entanglement
更新于2025-09-23 15:23:52
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Quantum error correction using weak measurements
摘要： The standard quantum error correction protocols use projective measurements to extract the error syndromes from the encoded states. We consider the more general scenario of weak measurements, where only partial information about the error syndrome can be extracted from the encoded state. We construct a feedback protocol that probabilistically corrects the error based on the extracted information. Using numerical simulations of one-qubit error correction codes, we show that our error correction succeeds for a range of the weak measurement strength, where (a) the error rate is below the threshold beyond which multiple errors dominate, and (b) the error rate is less than the rate at which weak measurement extracts information. We observe that error correction based on projective measurements is always superior to that based on weak measurements; so the latter is worthwhile only if the former is unavailable due to some reason, and error correction with too small a measurement strength should be avoided.
关键词： Projective measurement,Quantum error correction,Weak measurement,Quantum trajectory
更新于2025-09-23 15:22:29
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Quantum computing with neutral atoms
摘要： The power of quantum computation derives from algorithmic methods that exploit the availability of quantum superposition and entanglement to perform computations that are intractable with classical devices. The race is on to develop hardware that will unleash the promise of quantum algorithms. A handful of different types of hardware are currently being developed with the greatest efforts directed at superconducting, quantum-dot, trapped-ion, photonic, and neutral-atom approaches [1]. While all approaches have strengths and weaknesses, and are at different stages of development, the challenge of creating a practical design that can be scaled to a million or more qubits has not yet been met with any of the existing platforms.
关键词： neutral atoms,Rydberg states,Quantum computing,quantum error correction,qubits
更新于2025-09-23 15:21:21
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[Texts and Readings in Physical Sciences] Open Quantum Systems Volume 20 (Dynamics of Nonclassical Evolution) || Open Quantum System at Interface with Quantum Information
摘要： This chapter is devoted to the interface between open system ideas and the burgeoning field of quantum information. Quantum information is, as the name suggests, the broad name given to information tasks that make use of the laws of quantum mechanics. It encompasses within its purview, communication, computation and foundational information theoretical tasks. Information theoretic ideas pervade the whole of physics and make inroads beyond it. As it involves encoding, transmission and decoding of information as bits or qubits, all of which are very sensitive to their ambient environment, they provide a fruitful ground for the application of open system ideas. In fact, this chapter and the next one bear testimony to this.
关键词： quantum information,open quantum systems,quantum computation,quantum error correction,quantum communication
更新于2025-09-23 15:21:01
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[IEEE 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Sarajevo, Bosnia and Herzegovina (2019.9.2-2019.9.4)] 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - High-Capacity Single-Sideband Suppressed-Carrier Modulation with Integrated Optical Filter in Silicon-on-Insulator Technology
摘要： Powerful quantum error correction codes (QECCs) are required for stabilizing and protecting fragile qubits against the undesirable effects of quantum decoherence. Similar to classical codes, hashing bound approaching QECCs may be designed by exploiting a concatenated code structure, which invokes iterative decoding. Therefore, in this paper, we provide an extensive step-by-step tutorial for designing extrinsic information transfer (EXIT) chart-aided concatenated quantum codes based on the underlying quantum-to-classical isomorphism. These design lessons are then exempli?ed in the context of our proposed quantum irregular convolutional code (QIRCC), which constitutes the outer component of a concatenated quantum code. The proposed QIRCC can be dynamically adapted to match any given inner code using EXIT charts, hence achieving a performance close to the hashing bound. It is demonstrated that our QIRCC-based optimized design is capable of operating within 0.4 dB of the noise limit.
关键词： turbo codes,Quantum error correction,hashing bound.,EXIT charts
更新于2025-09-23 15:19:57
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Entanglement of genuinely entangled subspaces and states: Exact, approximate, and numerical results
摘要： Genuinely entangled subspaces (GESs) are those subspaces of multipartite Hilbert spaces that consist only of genuinely multiparty entangled pure states. They are natural generalizations of the well-known notion of completely entangled subspaces, which by definition are void of fully product vectors. Entangled subspaces are an important tool of quantum information theory as they directly lead to constructions of entangled states, since any state supported on such a subspace is automatically entangled. Moreover, they have also proven useful in the area of quantum error correction. In our recent contribution [M. Demianowicz and R. Augusiak, Phys. Rev. A 98, 012313 (2018)], we have studied the notion of a GES qualitatively in relation to so-called nonorthogonal unextendible product bases and provided a few constructions of such subspaces. The main aim of the present work is to perform a quantitative study of the entanglement properties of GESs. First, we show how one can attempt to compute analytically the subspace entanglement, defined as the entanglement of the least-entangled vector from the subspace, of a GES and illustrate our method by applying it to a new class of GESs. Second, we show that certain semidefinite programming relaxations can be exploited to estimate the entanglement of a GES and apply this observation to a few classes of GESs revealing that in many cases the method provides the exact results. Finally, we study the entanglement of certain states supported on GESs, which is compared to the obtained values of the entanglement of the corresponding subspaces, and find the white-noise robustness of several GESs. In our study we use the (generalized) geometric measure as the quantifier of entanglement.
关键词： Genuinely entangled subspaces,semidefinite programming,quantum error correction,generalized geometric measure,quantum information theory,geometric measure
更新于2025-09-12 10:27:22
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Generating higher-order quantum dissipation from lower-order parametric processes
摘要： The stabilisation of quantum manifolds is at the heart of error-protected quantum information storage and manipulation. Nonlinear driven-dissipative processes achieve such stabilisation in a hardware efficient manner. Josephson circuits with parametric pump drives implement these nonlinear interactions. In this article, we propose a scheme to engineer a four-photon drive and dissipation on a harmonic oscillator by cascading experimentally demonstrated two-photon processes. This would stabilise a four-dimensional degenerate manifold in a superconducting resonator. We analyse the performance of the scheme using numerical simulations of a realisable system with experimentally achievable parameters.
关键词： dissipation engineering,quantum information,quantum error correction,superconducting quantum computation
更新于2025-09-04 15:30:14