Recent advances in fabricating superconducting circuits have allowed large numbers of microwave resonators and superconducting qubits to be employed in such circuits, but shared quantum entanglement among the photonics states of the resonators has not been attempted. Theorists now present a proposal that uses superconducting circuits to simulate a particular many-body quantum model that until now has been experimentally inaccessible and to create a type of shared quantum entanglement with the simulation.
Recent advances in fabricating superconducting circuits have allowed large numbers of microwave resonators and superconducting qubits to be employed in such circuits, but shared quantum entanglement among the photonics states of the resonators has not been attempted. Theorists now present a proposal that uses superconducting circuits to simulate a particular many-body quantum model that until now has been experimentally inaccessible and to create a type of shared quantum entanglement with the simulation.
We present proposals to simulate many-body physics with superconducting circuits. The "body’’ to work with for superconducting circuits is the microwave photon and interaction is induced by the nonlinearity of the Josephson effect. We present two different approaches to simulate Bose-Hubbard physics, one based on a polariton scheme and another with nonlinear resonators. We also present a Dicke-model like simulator for ultrastrongly coupled Josephson junctions to a resonator and show a scheme for implementing long range interactions.
Quantum entanglement, one of the defining features of quantum mechanics, has been demonstrated in a variety of nonlinear spinlike systems. Quantum entanglement in linear systems has proven significantly more challenging, as the intrinsic energy level degeneracy associated with linearity makes quantum control more difficult. Here we demonstrate the quantum entanglement of photon states in two independent linear microwave resonators, creating N-photon NOON states (entangled states |N0> + |0N>) as a benchmark demonstration. We use a superconducting quantum circuit that includes Josephson qubits to control and measure the two resonators, and we completely characterize the entangled states with bipartite Wigner tomography. These results demonstrate a significant advance in the quantum control of linear resonators in superconducting circuits.
Abstract The Jaynes‐Cummings model describes the coupling between photons and a single two‐level atom in a simplified representation of light‐matter interactions. In circuit QED, this model is implemented by combining microwave resonators and superconducting qubits on a microchip with unprecedented experimental control. Arranging qubits and resonators in the form of a lattice realizes a new kind of Hubbard model, the Jaynes‐Cummings‐Hubbard model, in which the elementary excitations are polariton quasi‐particles. Due to the genuine openness of photonic systems, circuit QED lattices offer the possibility to study the intricate interplay of collective behavior, strong correlations and non‐equilibrium physics. Thus, turning circuit QED into an architecture for quantum simulation, i.e., using a well‐controlled system to mimic the intricate quantum behavior of another system too daunting for a theorist to tackle head‐on, is an exciting idea which has served as theorists’ playground for a while and is now also starting to catch on in experiments. This review gives a summary of the most recent theoretical proposals and experimental efforts.
Hybrid W entangled states are essential in quantum information processing, quantum communication, and quantum technology. In this Letter, we propose a simple method to prepare hybrid W entangled states between n superconducting (SC) qubits and n microwave resonators (MRs) in circuit QED. Only two basic operations are needed for the preparation of hybrid W states. The operational time decreases as the number of qubits increases. Since no ancillary cavity is required, the hardware resources for the state preparation are minimized. Because the state preparation does not involve any measurements, the hybrid W entangled states are generated in a deterministic way. Moreover, during the entire preparation, the high-energy levels of the SC qutrits remain unexcited, which greatly reduces decoherence of the SC qutrits. As an example, our numerical simulation demonstrates that high-fidelity preparation of the hybrid W entangled state of three SC qubits and three MRs is feasible within the current circuit QED technique. This method is universal and can be applied to generate hybrid W states of n matter qubits (e.g., atomic qubits, NV center qubits, quantum dot qubits, and magnon qubits) and n photonic qubits in various physical systems.
Quantum entanglement is an important resource for quantum information processing tasks. However, realistic multipartite entangled state production is very difficult. In this paper, we propose an efficient single-step scheme for generating many body Greenberger–Horne–Zeilinger (GHZ) states on superconducting circuits by using a superconducting transmission-line resonator (TLR) interact with [Formula: see text] superconducting transmon qubits. The distinct merit of our proposal is that it does not require the qubit-resonator coupling strengths to be the same, which is usually impractical experimentally, and thus is one of the main reasons for entanglement generation infidelity in previous single-step schemes. The removing of the uniform interaction requirement is achieved by modulating the qubits splitting frequencies with ac microwave fields, which results in tunable individual qubit-resonator coupling strength, and thus effective uniform qubit–qubit interaction Hamiltonian can be obtained. Since microwave control is conventional nowadays, our proposal can be directly tested experimentally, which makes previous multipartite entangled states generation schemes more efficient.
Quantum simulators are attractive as a means to study many-body quantum systems that are not amenable to classical numerical treatment. A versatile framework for quantum simulation is offered by superconducting circuits. In this perspective, we discuss how superconducting circuits allow the engineering of a wide variety of interactions, which, in turn, allows the simulation of a wide variety of model Hamiltonians. In particular, we focus on strong photon–photon interactions mediated by nonlinear elements. This includes on-site, nearest-neighbor, and four-body interactions in lattice models, allowing the implementation of extended Bose–Hubbard models and the toric code. We discuss not only the present state in analog quantum simulation but also future perspectives of superconducting quantum simulation, which open up when concatenating quantum gates in emerging quantum computing platforms.