Coherent router for quantum networks with superconducting qubits

Christensen, K. S.; Rasmussen, S. E.; Petrosyan, David; Zinner, N. T.

doi:10.1103/physrevresearch.2.013004

Cited by 18 publications

(13 citation statements)

References 56 publications

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“…This yields a simple linear coupling like in Eq. ( 75) [134]. We therefore focus on couplings beyond static linear couplings.…”

Section: Coupled Qubitsmentioning

confidence: 99%

The superconducting circuit companion -- an introduction with worked examples

Rasmussen,

Christensen,

Pedersen

et al. 2021

Preprint

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This article is a tutorial on the quantum treatment of superconducting electrical circuits. It is intended for new researchers with limited or no experience with the field, but should be accessible to anyone with a bachelor's degree in physics or similar. The tutorial has three parts. The first part introduces the basic methods used in quantum circuit analysis, starting from a circuit diagram and ending with a quantized Hamiltonian truncated to the lowest levels. The second part introduces more advanced methods supplementing the methods presented in the first part. The third part is a collection of worked examples of superconducting circuits. Besides the examples in the third part, the two first parts also includes examples in parallel with the introduction of the methods.

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“…This yields a simple linear coupling like in Eq. ( 75) [134]. We therefore focus on couplings beyond static linear couplings.…”

Section: Coupled Qubitsmentioning

confidence: 99%

The superconducting circuit companion -- an introduction with worked examples

Rasmussen,

Christensen,

Pedersen

et al. 2021

Preprint

Self Cite

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show abstract

“…We note here that we have performed the rotating wave approximation in order to arrive at the Hamiltonian [51]. The structure of the coupling is similar to XXZ-type Heisenberg couplings [52,53], but with some important modifications that we will now discuss.…”

Section: Implementation Of Coupled Qutrit Systemmentioning

confidence: 99%

Topological phases in interacting spin-1 systems

Alnor¹,

Bækkegaard²,

Zinner

2021

Preprint

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The transitions among different topological phases of quantum systems has become a focus area in recent decades. In particular, the question of how to realize and manipulate systems with nontrivial first Chern number is pursued both experimentally and theoretically. Here we go beyond typical spin 1/2 systems and consider both single and coupled spin 1 systems as a means of realizing higher first Chern numbers and studying the transitions between different topological phases. We show that rich topological phase diagrams can be realized by coupling two spin 1 systems using both numerical and analytical methods. Furthermore, we consider a concrete realization of spin 1 systems using superconducting circuits. This realization includes non-standard spin-spin interaction terms that may endanger the topological properties. However, as we argue here, the realistic circuit Hamiltonian including all terms should be expected to show the rich phase structure as well. This puts our predictions within reach of state-of-the-art experimental setups.

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“…Inspired by the superconducting circuit realizing the coherent quantum router in Ref. [38] we propose to implement the n-bit Toffoli gate and the CNOT n gate by connecting n transmon qubits [39,40] via Josephson junctions (with as small a paracitic capacitance as possible) to another transmon qubit, which we call the zeroth transmon, in correspondence with naming of the qubits in Sec. II.…”

Section: A Superconducting Circuit Implementationmentioning

confidence: 99%

Single-step implementation of high-fidelity n -bit Toffoli gates

et al. 2020

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The family of n-bit Toffoli gates, with the 2-bit Toffoli gate as the figurehead, are of great interest in quantum information as they can be used as universal gates and in quantum error correction, among other things. We present a single-step implementation of arbitrary n-bit Toffoli gates (up to a local change of basis), based on resonantly driving a single qubit that has a strong Ising coupling to n other qubits. The setup in the 2-qubit case turns out to be identical to the universal Barenco gate. The gate time and error are, in theory, independent of the number of control qubits, scaling better than conventional circuit decompositions. We note that our assumptions, namely strongly coupling n + 1 qubits and a driving frequency that scales with n, may break down for large systems. Still, our protocol could enhance the capabilities of intermediate scale quantum computers, and we discuss the prospects of implementing our protocol on trapped ions, Rydberg atoms, and on superconducting circuits. Simulations of the latter platform show that the Toffoli gate with two control bits attains fidelities of above 0.98 even in the presence of decoherence. We also show how similar ideas can be used to make a series of CNOT-gates in a single step. Lastly, we show how these can speed up the implementation of quantum error correcting codes, and simulate the encoding steps of the three-qubit bit flip code and the seven-qubit Steane code. arXiv:1910.07548v2 [quant-ph]

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Coherent router for quantum networks with superconducting qubits

Cited by 18 publications

References 56 publications

The superconducting circuit companion -- an introduction with worked examples

The superconducting circuit companion -- an introduction with worked examples

Topological phases in interacting spin-1 systems

Single-step implementation of high-fidelity n -bit Toffoli gates

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