Many spectroscopic techniques today rely on time-resolved measurements under short excitation pulses. Instead of using a chopped pump excitation, or ultrafast optical pulses, we expand on and apply the previously developed set of frequency domain methods to analyze the population level dynamics in rare-earth-doped media. By identifying the full frequency response of the gain medium, this method can accurately yield excited state lifetimes and can also be used to estimate transition cross-sections. The accuracy of the frequency domain methods are verified with Er3+-and Tm3+-doped fibers, and an Al2O3:Tm3+waveguide, recovering similar results as reported by time-resolved techniques. The complete frequency domain model presented here can be used in characterization of novel optical gain media, and can provide insights into population dynamics in solid state amplifiers and lasers.Many spectroscopic techniques today rely on time-resolved measurements under short excitation pulses. Instead of using a chopped pump excitation, or ultrafast optical pulses, we expand on and apply the previously developed set of frequency domain methods to analyze the population level dynamics in rare-earth-doped media. By identifying the full frequency response of the gain medium, this method can accurately yield excited state lifetimes and can also be used to estimate transition cross-sections. The accuracy of the frequency domain methods are verified with Er3+-and Tm3+-doped fibers, and an Al2O3:Tm3+waveguide, recovering similar results as reported by time-resolved techniques. The complete frequency domain model presented here can be used in characterization of novel optical gain media, and can provide insights into population dynamics in solid state amplifiers and lasers.

IEEE Journal of Selected Topics in Quantum ElectronicsFeb 15, 201810 citations

Adaptive Spectroscopy of Fast Two-Level-System Dynamics in Superconducting Qubits

Fabrizio Berritta, David Pahl, Lukas Pahl +15 more

Parasitic two-level-system (TLS) defects are a major source of energy relaxation and temporal instability in superconducting quantum processors. Our sub-second adaptive spectroscopy reveals telegraphic switching of TLSs with a characteristic timescale of a few seconds and spectral diffusion with diffusivity $D \approx 0.9~\mathrm{MHz}^2/\mathrm{s}$ . These timescales are about $3 \times 10^2$ times faster than what is observed in conventional nonadaptive spectroscopy, which typically requires hours of measurement time. We resolve such fast dynamics on a field-programmable gate array (FPGA)-based controller that enables measurement of frequency- and time-resolved relaxations with sub-second temporal resolution in flux-tunable superconducting qubits. We observe similar defect dynamics across multiple qubits in independently fabricated devices measured in different laboratories. We correlate TLS-induced fluctuations with gate-level errors using randomized benchmarking. Our results reveal a previously inaccessible regime of frequency-resolved TLS dynamics and redefine the timescales relevant to TLS-aware characterization and calibration of superconducting quantum processors.Parasitic two-level-system (TLS) defects are a major source of energy relaxation and temporal instability in superconducting quantum processors. Our sub-second adaptive spectroscopy reveals telegraphic switching of TLSs with a characteristic timescale of a few seconds and spectral diffusion with diffusivity $D \approx 0.9~\mathrm{MHz}^2/\mathrm{s}$. These timescales are about $3 \times 10^2$ times faster than what is observed in conventional nonadaptive spectroscopy, which typically requires hours of measurement time. We resolve such fast dynamics on a field-programmable gate array (FPGA)-based controller that enables measurement of frequency- and time-resolved relaxations with sub-second temporal resolution in flux-tunable superconducting qubits. We observe similar defect dynamics across multiple qubits in independently fabricated devices measured in different laboratories. We correlate TLS-induced fluctuations with gate-level errors using randomized benchmarking. Our results reveal a previously inaccessible regime of frequency-resolved TLS dynamics and redefine the timescales relevant to TLS-aware characterization and calibration of superconducting quantum processors.

quant-pharXiv:2608.02086Aug 4, 20260 citations

Dynamical Localization, Dissipation, and Repeated Measurements

Robert Graham

NATO ASI series. Series B : PhysicsJan 1, 19910 citations

Ion trap frequency measurement from fluorescence dynamics

Kota Saito, Ryoichi Saito, Takashi Mukaiyama

In this paper, we propose and demonstrate a new method for measuring the trap frequency from the fluorescence dynamics of an ion, initiated using fast trap-center displacement. Here, we observe the coherently excited motion of an ion in a harmonic trap using time-resolved fluorescence detection. Furthermore, Fourier analysis of the ion fluorescence signal was used to determine the trap frequency of an ion with high precision and reproducibility. The results show that our proposed method can be an alternative way to determine trap frequencies in an ion trap experiment.In this paper, we propose and demonstrate a new method for measuring the trap frequency from the fluorescence dynamics of an ion, initiated using fast trap-center displacement. Here, we observe the coherently excited motion of an ion in a harmonic trap using time-resolved fluorescence detection. Furthermore, Fourier analysis of the ion fluorescence signal was used to determine the trap frequency of an ion with high precision and reproducibility. The results show that our proposed method can be an alternative way to determine trap frequencies in an ion trap experiment.

Journal of Applied PhysicsSep 1, 20224 citations

The Macrodynamics of Digital Excitation

Masakazu Shoji

Springer eBooksJan 1, 19980 citations

D \approx 0.9~\mathrm{MHz}^2/\mathrm{s}

. These timescales are about

3 \times 10^2

times faster than what is observed in conventional nonadaptive spectroscopy, which typically requires hours of measurement time. We resolve such fast dynamics on a field-programmable gate array (FPGA)-based controller that enables measurement of frequency- and time-resolved relaxations with sub-second temporal resolution in flux-tunable superconducting qubits. We observe similar defect dynamics across multiple qubits in independently fabricated devices measured in different laboratories. We correlate TLS-induced fluctuations with gate-level errors using randomized benchmarking. Our results reveal a previously inaccessible regime of frequency-resolved TLS dynamics and redefine the timescales relevant to TLS-aware characterization and calibration of superconducting quantum processors.