Arrays of Cooper pair boxes coupled to a superconducting reservoir:  superradiance  and  revival

Rodrigues, DA; Györffy, B. L.; Spiller, Timothy P.

doi:10.1088/0953-8984/16/25/008

Cited by 7 publications

(9 citation statements)

References 26 publications

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“…Evidently, just as the occupation of the initial qubit states collapses and revives, so does the entanglement. This phenomenon was first noted by Rodrigues et al in a similar context [11].…”

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confidence: 59%

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Collapse and Revival of Entanglement between Qubits Interacting via a Quantum Bus

Jarvis,

Rodrigues,

Györffy

et al. 2008

Preprint

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We study the dynamics of the Jaynes-Cummings Model for two level systems (or qubits) interacting with a quantized single mode electromagnetic cavity (or 'quantum bus'). We show that there is a time in between the collapse and revival of Rabi oscillations when the state of the qubit sub-system, |ψ attractor , is largely independent of its initial state. This generalizes to many qubits the discovery by Gea-Banacloche for the one qubit case. The qubits in such 'attractor' states are not entangled either with the field or among themselves, even if they were in the initial state. Subsequently the entanglement between the qubits revives. Finally, it is argued that the collapse and revival of entanglement and the persistence of 'non-classicality' is a generic feature of multiple qubits interacting via a 'quantum bus'.

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supporting

confidence: 59%

“…Thus, in the language of quantum computation [7], we may regard the above system as a collection of qubits interacting via a quantum bus. Indeed our aim here is to study the 'collapse and revival' of entanglement between noninteracting qubits induced by a quantum bus [11].…”

mentioning

confidence: 99%

Collapse and Revival of Entanglement between Qubits Interacting via a Quantum Bus

Jarvis,

Rodrigues,

Györffy

et al. 2008

Preprint

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“…Another interesting feature of this system is the dynamics in the entanglement between the two qubits. We observe the time evolution of the system's mixed state tangle calculated from ρ q (t) and we plot line (d) to represent the tangle τ (t) that quantifies entanglement between the qubits at time t. Evidently, the two-qubit entanglement collapses and revives and this is similar to the phenomena discovered by C. Jarvis et al [43] and Rodrigues et al [44]. It can be seen that at the attractor times of 1 4 t r and 3 4 t r , the tangle values are zero, illustrating no entanglement exists between the qubits.…”

Section: Two Qubits-composite Spin Systemsupporting

confidence: 65%

Collapse and revival of entanglement between qubits coupled to a spin coherent state

Bahari

Spiller

Dooley

et al. 2018

Int. J. Quantum Inform.

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We extend study of the Jaynes-Cummings model involving a pair of identical two-level atoms (or qubits) interacting with a single mode quantized field. We investigate the effects of replacing the radiation field mode with a composite spin, comprising N qubits, or spin-1/2 particles. This model is relevant for physical implementations in superconducting circuit QED, ion trap and molecular systems. For the case of the composite spin prepared in a spin coherent state, we demonstrate the similarities of this set-up to the qubits-field model in terms of the time evolution, attractor states and in particular the collapse and revival of the entanglement between the two qubits. We extend our analysis by taking into account an effect due to qubit imperfections. We consider a difference (or 'mismatch') in the dipole interaction strengths of the two qubits, for both the field mode and composite spin cases. To address decoherence due to this mismatch, we then average over this coupling strength difference with distributions of varying width. We demonstrate in both the field mode and the composite spin scenarios that increasing the width of the 'error' distribution increases suppression of the coherent dynamics of the coupled system, including the collapse and revival of the entanglement between the qubits.

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confidence: 59%

Collapse and revival of “Schrödinger cat” states

et al. 2010

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We study the dynamics of the Jaynes-Cummings Model for an array of Nq two level systems (or qubits) interacting with a quantized single mode electromagnetic cavity (or quantum bus). For an initial cavity coherent state |α and the qubit system in a specified 'basin of attraction' in its Hilbert space, we demonstrate the oscillation of a superposition of two macroscopic quantum states between the qubit system and the field mode. From the perspective of either the qubit or the field system, there is collapse and revival of a 'Schrödinger Cat' state.Quantum superposition of macroscopically different states of matter are of fundamental conceptual interest in many fields of physics such as Measurement Theory [1], Quantum Optics [2], Macroscopic Quantum Tunnelling [3] and Quantum Computation [4]. Many of the relevant experiments revolve around the preparation of and measurement on a specific class of states called 'Schrödinger Cat' states [5]. These are quantum superpositions of states which correspond to two (or more) different values of a macroscopic variable, such as the magnetization or the electric field in the cases of a large spin cluster, or large photon number or phase in a cavity mode. In this letter we report the surprising discovery that in a Jaynes-Cummings model (JCM), which describes an array of two-level systems (qubits) interacting with a single cavity mode, the time evolution can be such that sometimes the radiation field and sometimes the qubit subsystem is in a 'Schrödinger Cat' state. In other words, a superposition of macroscopically different states can shift from one set of physical variables to another, as a function of time.The quantum dynamics of two-level systems (qubits), coupled to a single mode of an electromagnetic cavity, arise in many different physically interesting systems. These include Rydberg atoms [5], NMR studies of atomic nuclei [6,7], Cooper Pair Boxes [8], Cavity Quantum Electrodynamics [9], trapped ions [10] and Quantum Computing [4]. A very general and simple Hamiltonian that captures the relevant physics in all these fields is the JCM [11] (for one qubit) and its generalization for multiqubit systems by Tavis and Cummings [12]. Thus, our results are pertinent to a broad range of physical systems.One of the most interesting and surprising predictions of the JCM is the 'collapse and revival' of Rabi oscillations of the occupation probabilities for various qubit states as the system evolves, from an initial state which is a product of a coherent state |α for the radiation field, and a generic qubit state ψ Nq [2], where N q is the number of qubits. These remarkable dynamics occur only because both the matter and the cavity field are treated fully quantum mechanically. Indeed, our aim here is to study the 'collapse and revival' of 'Schrödinger cat'-like states in a multi-qubit subsystem, as well as in the cavity field .For clarity let us specify the multi-qubit JCM Hamiltonian, where each qubit labelled i has ground (excited) state |g i (|e i ) with energy ǫ g,i (ǫ e,i ). Up to...

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Arrays of Cooper pair boxes coupled to a superconducting reservoir: superradiance and revival

Cited by 7 publications

References 26 publications

Collapse and Revival of Entanglement between Qubits Interacting via a Quantum Bus

Collapse and Revival of Entanglement between Qubits Interacting via a Quantum Bus

Collapse and revival of entanglement between qubits coupled to a spin coherent state

Collapse and revival of “Schrödinger cat” states

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