The superconducting circuit companion -- an introduction with worked examples

Rasmussen, S. E.; Christensen, K. S.; Pedersen, S. P.; Kristensen, L. B.; Bækkegaard, T.; Loft, N. J. S.; Zinner, N. T.

doi:10.48550/arxiv.2103.01225

Cited by 4 publications

(8 citation statements)

References 113 publications

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“…The coupling of two spin 1, or two qutrits, using superconducting circuits has been investigated in [40], and details on how the effective Hamiltonian is derived from the circuit can be found also in [51], including a discussion of the parameters involved. A lumped circuit element drawing of the system, which we will also use here, can be seen in fig.…”

Section: Implementation Of Coupled Qutrit Systemmentioning

confidence: 99%

“…using an outer product operator notation with the qutrits states denoted by 0, 1, and 2, respectively. 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%

“…By adding drive lines to the circuit, we can physically realize the missing spin-matrices that would give rise to a non-trivial Chern-number. As discussed in [51], multilevel expansions of superconducting circuits can be modified by adding suitable drive lines. Using this technique we can control the S x or S y terms for each of the two qutrits.…”

Section: Implementation Of Coupled Qutrit Systemmentioning

confidence: 99%

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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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Section: Implementation Of Coupled Qutrit Systemmentioning

confidence: 99%

Section: Implementation Of Coupled Qutrit Systemmentioning

confidence: 99%

Section: Implementation Of Coupled Qutrit Systemmentioning

confidence: 99%

See 1 more Smart Citation

Topological phases in interacting spin-1 systems

Alnor¹,

Bækkegaard²,

Zinner

2021

Preprint

Self Cite

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show abstract

“…The model is a generic model of interacting two level systems with many possible implementations. Of particular note is germanium quantum dots [23,31] and superconducting circuits [24,25,32]. A possible implementation using superconducting circuits is proposed in the Supplemental Material.…”

Section: (B)mentioning

confidence: 99%

“…This resonator is not modelled directly to keep the simulations simpler, but it is instead modeled by letting qubit 1 decay. To reach this model, we first write the Lagrangian for the circuit [32,34,35]…”

Section: Superconducting Circuit Implementationmentioning

confidence: 99%

Quantum Wheatstone Bridge

Poulsen,

Santos,

Zinner

2021

Preprint

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We propose a quantum Wheatstone bridge as a fully quantum analogue to the classical version. The bridge is a few-body boundary-driven spin chain exploiting quantum effects to gain an enhanced sensitivity to an unknown coupling. The sensitivity is explained by a drop in population of an entangled Bell state due to destructive interference as the controllable coupling approaches the unknown coupling. A simple criteria for the destructive interference is found, and an approximate expression for the width of the drop is derived. The sensitivity to the unknown coupling is quantified using the quantum Fisher information, and we show that the state of the bridge can be measured indirectly through the spin current. Our results are generic in the sense that several of the current state-of-the-art quantum platforms could be used as a means of realization. The quantum Wheatstone bridge may thus find use in fields such as sensing and metrology using near-term quantum devices.

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Noisy intermediate-scale quantum computers

Cheng

Deng

et al. 2023

Front. Phys.

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Quantum computers have made extraordinary progress over the past decade, and significant milestones have been achieved along the path of pursuing universal fault-tolerant quantum computers. Quantum advantage, the tipping point heralding the quantum era, has been accomplished along with several waves of breakthroughs. Quantum hardware has become more integrated and architectural compared to its toddler days. The controlling precision of various physical systems is pushed beyond the fault-tolerant threshold. Meanwhile, quantum computation research has established a new norm by embracing industrialization and commercialization. The joint power of governments, private investors, and tech companies has significantly shaped a new vibrant environment that accelerates the development of this field, now at the beginning of the noisy intermediate-scale quantum era. Here, we first discuss the progress achieved in the field of quantum computation by reviewing the most important algorithms and advances in the most promising technical routes, and then summarizing the next-stage challenges. Furthermore, we illustrate our confidence that solid foundations have been built for the fault-tolerant quantum computer and our optimism that the emergence of quantum killer applications essential for human society shall happen in the future.

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The superconducting circuit companion -- an introduction with worked examples

Cited by 4 publications

References 113 publications

Topological phases in interacting spin-1 systems

Topological phases in interacting spin-1 systems

Quantum Wheatstone Bridge

Noisy intermediate-scale quantum computers

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