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The coherence of superconducting quantum computers is severely limited by material defects that create parasitic two-level-systems (TLS). Progress is complicated by lacking understanding how TLS are created and in which parts of a qubit…

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…

While two-level systems (TLS) in superconducting qubits are known to introduce phonon-mediated energy dissipation channels, many-body TLS systems themselves can also act as a distinct dissipation channel whose effect on qubit energy…

Quantum Physics · Physics 2026-03-17 Xue-Yi Guo

Two-level systems (TLS) of unclear physical origin are a major contributor to decoherence in superconducting qubits. The interactions of individual TLS with a qubit can be detected via various spectroscopic methods, most of which have…

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

Superconducting microwave resonators are critical to quantum computing and sensing technologies. Additionally, they are common proxies for superconducting qubits when determining the effects of performance-limiting loss mechanisms such as…

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

Material disorders are one of the major sources of noise and loss in solid-state quantum devices, whose behaviors are often modeled as two-level systems (TLSs) formed by charge tunneling between neighboring sites. However, the role of their…

Superconducting qubit lifetimes must be both long and stable to provide an adequate foundation for quantum computing. This stability is imperiled by two-level systems (TLSs), currently a dominant loss mechanism, which exhibit slow spectral…

Quantum Physics · Physics 2024-02-28 Ted Thorbeck , Andrew Eddins , Isaac Lauer , Douglas T. McClure , Malcolm Carroll

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 $\overline{T_{1}}$…

Noise within solid-state systems at low temperatures, where many of the degrees of freedom of the host material are frozen out, can typically be traced back to material defects that support low-energy excitations. These defects can take a…

Quantum Physics · Physics 2024-10-28 Mo Chen , John Clai Owens , Harald Putterman , Max Schäfer , Oskar Painter

Two-level system fluctuators (TLS's) in the tunnel barrier of a Josephson junction have recently been demonstrated to cause novel energy splittings in spectroscopic measurements of superconducting phase qubits. With their strong coupling to…

Quantum Physics · Physics 2015-05-13 L. Tian , K. Jacobs

In the microscopic world, multipartite entanglement has been achieved with various types of nanometer sized two-level systems such as trapped ions, atoms and photons. On the macroscopic scale ranging from micrometers to millimeters, recent…

Superconductivity · Physics 2011-08-12 G. J. Grabovskij , P. Bushev , J. H. Cole , C. Müller , J. Lisenfeld , A. Lukashenko , A. V. Ustinov

Increasing and stabilizing the coherence of superconducting quantum circuits and resonators is of utmost importance for various technologies ranging from quantum information processors to highly sensitive detectors of low-temperature…

Disordered Systems and Neural Networks · Physics 2021-04-09 Shlomi Matityahu , Hartmut Schmidt , Alexander Bilmes , Alexander Shnirman , Georg Weiss , Alexey V. Ustinov , Moshe Schechter , Jürgen Lisenfeld

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

The innate complexity of solid state physics exposes superconducting quantum circuits to interactions with uncontrolled degrees of freedom degrading their coherence. By using a simple stabilization sequence we show that a superconducting…

The two-level systems (TLSs) naturally occurring in Josephson junctions constitute a major obstacle for the operation of superconducting phase qubits. Since these TLSs can possess remarkably long decoherence times, we show that such TLSs…

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

Materials defects in Josephson junctions (JJs), often referred to as two-level systems (TLS), couple to superconducting qubits and are a critical bottleneck for scalable quantum processors. Despite their importance, understanding the…

Here we find the increase in 1/f noise of superconducting resonators at low temperatures to be completely incompatible with the standard tunneling model (STM) of Two Level Systems (TLS), which has been used to describe low-frequency noise…

Two-level system (TLS) defects constitute a major decoherence source of quantum information science, but they are generally less understood at material interfaces than in deposited films. Here we study surface TLSs at the metal-air…

Applied Physics · Physics 2026-02-24 Chih-Chiao Hung , Tim Kohler , Kevin D. Osborn