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Two-level systems (TLS) are the major source of dephasing of spin qubits in numerous quantum computing platforms. In spite of much effort, it has been difficult to substantially mitigate the effects of this noise or, in many cases, to fully…

Quantum Physics · Physics 2025-07-25 Yujun Choi , S. N. Coppersmith , Robert Joynt

Microscopic two-level systems (TLS) -- ubiquitous atomic-scale defects in solid-state quantum devices -- are a dominant source of qubit decoherence, yet their role is often considered local and short-memoried. Here, we report the…

Superconducting circuits are a leading platform for quantum computing. However, their coherence times are still limited and exhibit temporal fluctuations. Those phenomena are often attributed to the coupling between qubits and material…

Quantum Physics · Physics 2022-10-13 Xinyuan You , Ziwen Huang , Ugur Alyanak , Alexander Romanenko , Anna Grassellino , Shaojiang Zhu

Quantum sensors and qubits are usually two-level systems (TLS), the quantum analogs of classical bits which assume binary values '0' or '1'. They are useful to the extent to which they can persist in quantum superpositions of '0' and '1' in…

Quantum Physics · Physics 2024-01-19 A. Beckert , M. Grimm , N. Wili , R. Tschaggelar , G. Jeschke , G. Matmon , S. Gerber , M. Müller , G. Aeppli

A major issue for the implementation of large scale superconducting quantum circuits is the interaction with interfacial two-level system defects (TLS) that leads to qubit relaxation and impedes qubit operation in certain frequency ranges…

We study the dephasing of an individual high-frequency tunneling two-level system (TLS) due to its interaction with an ensemble of low-frequency thermal TLSs which are described by the standard tunneling model (STM). We show that the…

Disordered Systems and Neural Networks · Physics 2016-04-20 Shlomi Matityahu , Alexander Shnirman , Gerd Schön , Moshe Schechter

We benchmark the decoherence of superconducting qubits to examine the temporal stability of energy-relaxation and dephasing. By collecting statistics during measurements spanning multiple days, we find the mean parameters $\overline{T_{1}}$…

The anomalous low-temperature properties of glasses arise from intrinsic excitable entities, so-called tunneling Two-Level-Systems (TLS), whose microscopic nature has been baffling solid-state physicists for decades. TLS have become…

Motivated by recent experiments with Josephson-junction circuits we reconsider decoherence effects in quantum two-level systems (TLS). On one hand, the experiments demonstrate the importance of 1/f noise, on the other hand, by operating at…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Alexander Shnirman , Yuriy Makhlin , Gerd Schön

Material defects fundamentally limit the coherence times of superconducting qubits, and manufacturing completely defect-free devices is not yet possible. Therefore, understanding the interactions between defects and a qubit in a real…

Material defects give rise to parasitic two-level systems (TLS) which present a major source of decoherence in superconducting qubits. Here, we study a strongly coupled TLS that resides in the tunnel barrier of transmon qubit. We use…

Quantum Physics · Physics 2026-05-05 J. Lisenfeld , A. K. Händel , A. Bilmes , A. V. Ustinov

Since the very first experiments, superconducting circuits have suffered from strong coupling to environmental noise, destroying quantum coherence and degrading performance. In state-of-the-art experiments, it is found that the relaxation…

Mesoscale and Nanoscale Physics · Physics 2015-08-04 Clemens Müller , Jürgen Lisenfeld , Alexander Shnirman , Stefano Poletto

Parasitic two-level-system (TLS) defects are one of the major factors limiting the coherence times of superconducting qubits. Although there has been significant progress in characterizing basic parameters of TLS defects, exact mechanisms…

Superconducting quantum computing is experiencing a tremendous growth. Although major milestones have already been achieved, useful quantum-computing applications are hindered by a variety of decoherence phenomena. Decoherence due to…

Quantum Physics · Physics 2022-10-21 J. H. Béjanin , Y. Ayadi , X. Xu , C. Zhu , H. R. Mohebbi , M. Mariantoni

We study the decoherence dynamics of a qubit coupled to a quantum two-level system (TLS) in addition to its weak coupling to a background environment. We analyze the different regimes of behaviour that arise as the values of the different…

Superconductivity · Physics 2007-05-23 S. Ashhab , J. R. Johansson , Franco Nori

We investigate the decoherence of a qubit coupled to either a quantum two-level system (TLS) again coupled to an environment, or a classical fluctuator modeled by random telegraph noise. In order to do this we construct a model for the…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Henry J. Wold , Håkon Brox , Yuri M. Galperin , Joakim Bergli

Recent studies have shown that parasitic two-level systems (TLS) in superconducting qubits, which are a leading source of decoherence, can have relaxation times longer than the qubits themselves. However, the standard techniques used to…

Quantum sensing and computation can be realized with superconducting microwave circuits. Qubits are engineered quantum systems of capacitors and inductors with non-linear Josephson junctions. They operate in the single-excitation quantum…

We investigate the pure dephasing of a Josephson qubit due to the spectral diffusion of two-level systems that are close to resonance with the qubit. We identify the parameter regime in which this pure dephasing rate can be of the order of…

Quantum Physics · Physics 2024-05-02 Shlomi Matityahu , Alexander Shnirman , Moshe Schechter

The proper functioning of some micro-fabricated novel quantum devices, such as superconducting resonators and qubits, is severely affected by the presence of parasitic structural material defects known as tunneling two-level-systems (TLS).…

Superconductivity · Physics 2022-02-01 Octavio de los Santos-Sánchez , Ricardo Román-Ancheyta
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