Qubit-oscillator systems in the ultrastrong-coupling regime and their potential for preparing nonclassical states

By Sahel Ashhab, Franco Nori. 2009

302 citations recorded by the source corpus.

We consider a system composed of a two-level system (i.e., a qubit) and a harmonic oscillator in the ultrastrong-coupling regime, where the coupling strength is comparable to the qubit and oscillator energy scales. Special emphasis is placed on the possibility of preparing nonclassical states in this system. These nonclassical states include squeezed states, Schroedinger-cat states, and entangled states. We start by comparing the predictions of a number of analytical methods that can be used to describe the system under different assumptions, thus analyzing the properties of the system in various parameter regimes. We then examine the ground state of the system and analyze its nonclassical properties. We finally discuss some questions related to the possible experimental observation of the nonclassical states and the effect of decoherence.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/f20a599c89d63dce8340fa2037aa2ec36d596bab

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Citations in the corpus

Colloquium: Stimulating uncertainty: Amplifying the quantum vacuum with superconducting circuits (2011, background): “In addition to the quantum vacuum amplification effects discussed in this review, superconducting circuits have also been proposed for realizing systems with ultrastrong atom-cavity coupling (Ashhab and Nori, 2010; Nataf and Ciuti, 2010; Peropadre et al., 2010).”
Hybrid quantum circuits: Superconducting circuits interacting with other quantum systems (2012, methodology): “However, in the ultrastrongcoupling regime (Ashhab and Nori, 2010), the counterrotating terms also play an important role and cannot be neglected.”
Breakdown of gauge invariance in ultrastrong-coupling cavity QED (2018, background): “However, already for a single dipole, a value of ζC 1 results in a qualitative change in the ground state of the quantum Rabi model [48,57,61], which is associated with an exponential closing of the energy gap between the lowest two states and a large occupation of the photonic mode.”
Multiphoton quantum Rabi oscillations in ultrastrong cavity QED (2015, unknown): “[28–36]).”
Microwave photonics with superconducting quantum circuits (2017, background): “A correct treatment of decoherence, input-output, and correlation functions for an ultrastrongly coupled system requires considering how operators induce transitions between eigenstates of the system [430, 433, 441, 442].”
Open quantum systems with local and collective incoherent processes: Efficient numerical simulations using permutational invariance (2018, background): “The rich phenomenology which becomes then observable [92, 96– 98, 240–259] has led to a remarkable interest in those nonperturbative regimes, which have been experimentally realized in a number of experimental implementations well described, at least in first approximation [260–264], by the Dicke mo”