Tunable coupling of transmission-line microwave resonators mediated by an rf SQUID

Wulschner, F.; Goetz, Jan; Koessel, F. R.; Hoffmann, E.; Baust, A.; Eder, Peter; Fischer, Michael; Haeberlein, M.; Schwarz, Martin; Pernpeintner, Matthias; Xie, Edwar; Zhong, L.; Zollitsch, Christoph W.; Peropadre, Borja; Ripoll, Juan-Jose Garcia; Solano, E.; Fedorov, Kirill G.; Menzel, E. P.; Deppe, Frank; Marx, Achim; Gross, Rudolf

doi:10.1140/epjqt/s40507-016-0048-2

Cited by 67 publications

(57 citation statements)

References 48 publications

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“…However, their coupling is determined by the fixed geometric arrangement of the resonators, resulting in a static coupling g bs that can not be switched off. In order to make the coupling switchable, different schemes have been proposed theoretically [23,24] and implemented experimentally [13][14][15]. All these proposals are based on superconducting rings acting as tunable couplers (cf.…”

Section: Boson Sampling With Superconducting Circuitsmentioning

confidence: 99%

“…All the above operations can be performed deterministically and with high fidelity on state-of-the-art superconducting devices with little design modifications with respect to current setups [12]. As demonstrated independently in [13] and in [14,15], these missing ingredients are relatively easy to integrate in superconducting architectures. This guarantees the scalability of our proposal and suggest superconducting platforms as a major physical candidate to the realization of large scale boson sampling experiments.…”

Section: Introductionmentioning

confidence: 99%

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Proposal for Microwave Boson Sampling

et al. 2016

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The first post-classical computation will most probably be performed not on a universal quantum computer, but rather on a dedicated quantum hardware. A strong candidate for achieving this is represented by the task of sampling from the output distribution of linear quantum optical networks. This problem, known as boson sampling, has recently been shown to be intractable for any classical computer, but it is naturally carried out by running the corresponding experiment. However, only small scale realizations of boson sampling experiments have been demonstrated to date. Their main limitation is related to the non-deterministic state preparation and inefficient measurement step. Here, we propose an alternative setup to implement boson sampling that is based on microwave photons and not on optical photons. The certified scalability of superconducting devices indicates that this direction is promising for a large-scale implementation of boson sampling and allows for more flexible features like arbitrary state preparation and efficient photon-number measurements.

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Section: Boson Sampling With Superconducting Circuitsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proposal for Microwave Boson Sampling

et al. 2016

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“…There can be two possibilities to control the qubit-qubit interaction in scalable circuit-QED design. One is to control the resonator-resonator coupling by using a intervening dc-SQUID [28], flux qubit [37,38,39,40], Josephson ring modulator [41], or transmon qubit [42]. On the other hand one can try to tune the coupling between qubit and transmission line resonator by controlling the qubit frequency [29,30,31,32] or a coupling element inserted between qubit and resonator [33,34,35,36].…”

Section: Introductionmentioning

confidence: 99%

Scalable quantum computing model in the circuit-QED lattice with circulator function

Kim

2017

Quantum Inf Process

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We propose a model for a scalable quantum computing in the circuit-quantum electrodynamics(QED) architecture. In the Kagome lattice of qubits three qubits are connected to each other through a superconducting three-junction flux qubit at the vertices of the lattice. By controlling one of the three Josephson junction energies of the intervening flux qubit we can achieve the circulator function that couples arbitrary pair of two qubits among three. This selective coupling enables the interaction between two nearest neighbor qubits in the Kagome lattice, and further the two-qubit gate operation between any pair of qubits in the whole lattice by performing consecutive nearest neighbor two-qubit gates.

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“…Achieving tunable couplings between circuit elements is a crucial step. Tunable strong coupling among superconducting elements has been achieved in several ways, using both superconducting quantum interference devices (SQUIDs) and qubits [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Recently, structured arrays of microwave superconducting resonators with SQUID tunable couplings [20][21][22] have been investigated on dedicated simulations of many-body models with engineered interactions [35][36][37][38][39].…”

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confidence: 99%

“…1, which can be made from finite sections of superconducting transmission line [18] or stripline [21,22]. The resonators couplings are mediated by SQUID elements.…”

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confidence: 99%

Staggered quantum walks with superconducting microwave resonators

2017

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The staggered quantum walk model on a graph is defined by an evolution operator that is the product of local operators related to two or more independent graph tessellations. A graph tessellation is a partition of the set of nodes that respects the neighborhood relation. Flip-flop coined quantum walks with the Hadamard or Grover coins can be expressed as staggered quantum walks by converting the coin degree of freedom into extra nodes in the graph. We propose an implementation of the staggered model with superconducting microwave resonators, where the required local operations are provided by the nearest neighbor interaction of the resonators coupled through superconducting quantum interference devices. The tunability of the interactions makes this system an excellent toolbox for this class of quantum walks. We focus on the one-dimensional case and discuss its generalization to a more general class known as triangle-free graphs.Quantum walks are the quantum generalization of random walks, and form the building blocks in designing quantum search algorithms outperforming the similar classical ones [1]. The two main paradigms in this respect are the coined discrete-time quantum walk (DTQW) [2] and the continuoustime quantum walk (CTQW) [3]. In one-dimensional (1D) DTQWs, a two-level quantum system works as a coin, whose quantum property to exist in a superposition of states gives the distinct ballistic spreading of the walker encoded in a set of discrete states. In CTQWs, it is the excitation exchange between the neighboring sites, in a lattice, that directly works as a walker without the need of a coin. Typically a tight-biding Hamiltonian followed by a linear coupling between excitations in bosonic modes suffices to implement the CTQW model, making its implementation convenient (See Ref. [4] for an example with nanomechanical resonators). However, when the data structure is a lattice with dimension less than four, search algorithms based on the standard CTQW do not outperform the classical algorithms based on random walks [5].Recently, a general class of coinless discrete-time quantum walks was proposed-the staggered quantum walk (SQW) [6][7][8], which includes the quantum walks studied in Refs. [9,10] as particular cases. This model also includes as particular cases the flip-flop coined DTQWs with Hadamard and Grover coins and the entire Szegedy's quantum walk model [11]. In the language of graph theory, the required unitary operators (not Hamiltonians) can be obtained by a graphical method based on graph tessellations. A tessellation is a partition of the set of nodes into cliques; that is, each element of the partition is a clique. A clique is a subgraph that is complete, namely, all nodes of a clique are neighbors.We have proposed an extension of the SQW model, called SQW with Hamiltonians [12], which uses the graph tessellations to define local Hamiltonians instead of the local unitary evolution operators. The extended model includes the quantum walks analyzed in Ref.[13] as particular cases. The SQW with H...

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Tunable coupling of transmission-line microwave resonators mediated by an rf SQUID

Cited by 67 publications

References 48 publications

Proposal for Microwave Boson Sampling

Proposal for Microwave Boson Sampling

Scalable quantum computing model in the circuit-QED lattice with circulator function

Staggered quantum walks with superconducting microwave resonators

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