A tunable quantum dissipator for active resonator reset in circuit QED

In the framework of bilinear control systems, we present reachable sets of coherently controllable open quantum systems with switchable coupling to a thermal bath of arbitrary temperature T ≥ 0. The core problem boils down to studying points in the standard simplex amenable to two types of controls that can be used interleaved:(i) permutations within the simplex, (ii) contractions by a dissipative one-parameter semigroup. Our work illustrates how the solutions of the core problem pertain to the reachable set of the original controlled Markovian quantum system. We completely characterize the case T = 0 and present inclusions for T > 0.

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“…1. By Lemma 1 (13) so we may apply Lemma 2 and 3 to B 0 . The former one, in particular, implies that for arbitrary y ∈ R n one has…”

Section: A Reachability Results In the Low-temperature Limit 1) Globmentioning

confidence: 99%

Reachable Sets from Toy Models to Controlled Markovian Quantum Systems

Dirr

vom

Schulte‐Herbrüggen

2019

2019 IEEE 58th Conference on Decision and Control (CDC)

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“…In terms of coupled dissipative systems, the EP separates the system between the overdamped and underdamped regimes being the point of critical coupling. It follows from the dynamics of the coupled system that at this point, the energy is transferred between the two resonators optimally fast without back and forth oscillation [42,56]. In particular, the rate of heat transfer at zero detuning is given by…”

Section: Exceptional Pointsmentioning

confidence: 99%

“…5). By adding voltage-tunable dissipation to a system of two resonators with tunable coupling, our approach provides a conceptually higher level of control compared to the commonly studied systems which only have tunable coupling between the resonators [42,[50][51][52][53][54][55][56][57]. Hence, our work demonstrates a platform to control the dissipation and, consequently, local heat transport between neighboring nodes in a quantum electrical circuit.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the precise engineering of energy flows between different parts of the circuit in scalable architectures is of utmost importance since heat is a typical source of decoherence in qubits [38,39]. In many error correction codes, qubits are repeatedly initialized, which requires fast and efficient cooling schemes [40][41][42]. It is also of great importance to reset the qubit readout resonators, for example, using pulse shaping [43,44].…”

Section: Introductionmentioning

confidence: 99%

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Exceptional points in tunable superconducting resonators

et al. 2019

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Superconducting quantum circuits are potential candidates to realize a large-scale quantum computer. The envisioned large density of integrated components, however, requires a proper thermal management and control of dissipation. To this end, it is advantageous to utilize tunable dissipation channels and to exploit the optimized heat flow at exceptional points (EPs). Here, we experimentally realize an EP in a superconducting microwave circuit consisting of two resonators. The EP is a singularity point of the effective Hamiltonian, and corresponds to critical damping with the most efficient heat transfer between the resonators without back and forth oscillation of energy. We observe a crossover from underdamped to overdamped coupling across the EP by utilizing photonassisted tunneling as an in situ tunable dissipative element in one of the resonators. These methods can be used to obtain fast dissipation, for example, for initializing qubits to their ground states. In addition, these results pave the way for thorough investigation of parity-time symmetry and the spontaneous symmetry breaking at the EP in superconducting quantum circuits operating at the level of single energy quanta.

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“…Proposals along this line include the dissipator as a frequency-tunable Josephson junction with small quality factor (≈ 100). [108] A design where two resonators, one with high quality factor and another one tunable and coupled to the ground by a resistor, has been studied in refs. [83,104].…”

Section: Tuning Of Dissipationmentioning

confidence: 99%

Engineering Dissipation with Resistive Elements in Circuit Quantum Electrodynamics

Cattaneo

Paraoanu

2021

Adv Quantum Tech

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The importance of dissipation engineering ranges from universal quantum computation to non‐equilibrium quantum thermodynamics. In recent years, more and more theoretical and experimental studies have shown the relevance of this topic for circuit quantum electrodynamics, one of the major platforms in the race for a quantum computer. This article discusses how to simulate thermal baths by inserting resistive elements in networks of superconducting qubits. Apart from pedagogically reviewing the phenomenological and microscopic models of a resistor as thermal bath with Johnson–Nyquist noise, the paper introduces some new results in the weak coupling limit, showing that the most common examples of open quantum systems can be simulated through capacitively coupled superconducting qubits and resistors. The aim of the manuscript, written with a broad audience in mind, is to be both an instructive tutorial about how to derive and characterize the Hamiltonian of general dissipative superconducting circuits with capacitive coupling, and a review of the most relevant and topical theoretical and experimental works focused on resistive elements and dissipation engineering.

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A tunable quantum dissipator for active resonator reset in circuit QED

Cited by 12 publications

References 48 publications

Reachable Sets from Toy Models to Controlled Markovian Quantum Systems

Reachable Sets from Toy Models to Controlled Markovian Quantum Systems

Exceptional points in tunable superconducting resonators

Engineering Dissipation with Resistive Elements in Circuit Quantum Electrodynamics

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