This publication presents a straightforward experimental study measuring the energy-relaxation time, or T1, of a superconducting qubit on IBM Quantum hardware. It explains the basic idea behind the test, preparing the qubit in the excited state, letting it sit for different delay times, and measuring how quickly it decays back toward the ground state, then fits the results to an exponential decay model that accounts for measurement imperfections. Using the ibm_torino backend on qubit Q0, the paper reports a measured T1 of about 132 microseconds, based on a single sweep of 25 delay values with 4096 shots per point. Along with the result, the publication includes the theoretical model, experimental setup, raw decay data, and discussion of limitations such as noise, drift, and fit-quality concerns, making it both a concise report of the measurement and a reproducible example for readers interested in quantum hardware characterization.
This publication presents a straightforward experimental study measuring the energy-relaxation time, or T1, of a superconducting qubit on IBM Quantum hardware. It explains the basic idea behind the test, preparing the qubit in the excited state, letting it sit for different delay times, and measuring how quickly it decays back toward the ground state, then fits the results to an exponential decay model that accounts for measurement imperfections. Using the ibm_torino backend on qubit Q0, the paper reports a measured T1 of about 132 microseconds, based on a single sweep of 25 delay values with 4096 shots per point. Along with the result, the publication includes the theoretical model, experimental setup, raw decay data, and discussion of limitations such as noise, drift, and fit-quality concerns, making it both a concise report of the measurement and a reproducible example for readers interested in quantum hardware characterization.
We report evidence consistent with non-exponential decoherence in superconducting transmon qubits. Ramsey interferometry data from five qubits on IBM Quantum hardware show that a stretched-exponential model f(t) = exp(-(t/T2 ) beta) fits the observed decay better than the standard exponential (beta = 1). On our primary qubit (Q0), we measure beta = 2.06 with R2 = 0.9964 versus R2 = 0.9586 for the exponential, with Bayesian Information Criterion favoring the stretched model by 46 units. While non-exponential decay in superconducting qubits has been previously observed in the context of 1/f noise [4], the present work provides a systematic multi-qubit characterization with a fully reproducible protocol and proposes a falsifiable geometry-dependent prediction (RAB != 1) that distinguishes this framework from collapse-model alternatives.
Fluxonium superconducting qubits have demonstrated long coherence times and high single- and two-qubit gate fidelities, making them a favorable building block for superconducting quantum processors. We investigate the dominant limitations to fluxonium qubit energy relaxation time T1 using a set of eight planar, aluminum-on-silicon qubits. We find that a circuit-based model for capacitive dielectric loss best captures the frequency dependence of T1, which we analyze within both a two-level and a six-level energy relaxation model. We convert the measured T1 into an effective capacitive quality factor QCeff to compare qubits on equal footing, accounting for independently estimated contributions from 1/f flux noise and radiative loss to the control and readout circuitry. We apply this methodology to compare qubits from two fabrication processes: a baseline process and one that applies a fluorine-based wet treatment prior to Josephson junction deposition. We resolve a small improvement of (13.8 ± 8.4)% in the process mean QCeff, indicating that the fluorine treatment may have reduced loss from the metal-substrate interface, but did not address the primary source of loss in these fluxonium qubits.
Measuring the state of qubits is one of the fundamental operations of a quantum computer. Currently, state-of-the-art high-fidelity single-shot readout of superconducting qubits relies on parametric amplifiers at the millikelvin stage. However, parametric amplifiers are challenging to scale beyond hundreds of qubits owing to practical size and power limitations. Nanobolometers have a multitude of properties that are advantageous for scalability and have recently shown sensitivity and speed promising for qubit readout, but such thermal detectors have not been demonstrated for this purpose. In this work, we utilize an ultrasensitive bolometer in place of a parametric amplifier to experimentally demonstrate single-shot qubit readout. With a readout duration of 13.9μs, we achieve a single-shot fidelity of 0.618 which is mainly limited by the energy relaxation time of the qubit, T1=28μs. Without the T1 errors, we find the fidelity to be 0.927. In the future, high-fidelity single-shot readout may be achieved by straightforward improvements to the chip design and experimental setup, and perhaps most interestingly by the change of the bolometer absorber material to reduce the readout time to the hundred-nanosecond level and beyond.
We analyze the dynamics of a qubit-resonator system coupled with a thermal bath and external electromagnetic fields. Using the evolution equations for the set of Heisenberg operators that describe the whole system, we derive an expression for the resonator field, that includes the resonator-drive, the resonator-bath, and resonator-qubit interactions. The renormalization of the resonator frequency, caused by the qubit-resonator interaction, is accounted for. Using the solutions for the resonator field, we derive the equation that describes the qubit dynamics. The dependence of the qubit evolution during the measurement time on the fidelity of a single-shot measurement is studied. The relation between the fidelity and measurement time is shown explicitly. We proposed a novel adiabatic method for the phase qubit measurement. The method utilizes a low-frequency, quasi-classical resonator inductively coupled to the qubit. The resonator modulates the qubit energy, and the back reaction of the qubit causes a shift in the phase of the resonator. The resonator phase shift can be used to determine the qubit state. We have simulated this measurement taking into the account the energy levels outside the phase qubit manifold. We have shown that, for qubit frequencies in the range of 8-12GHZ, a resonator frequency of 500 MHz and a measurement time of 100 ns, the phase difference between the two qubit states is greater than 0.2 rad. This phase difference exceeds the measurement uncertainty, and can be detected using a classical phase-meter. A fidelity of 0.9999 can be achieved for a relaxation time of 0.5 ms. We also model and simulate a microstrip-SQUID amplifier of frequency about 500 MHz, which could be used to amplify the resonator oscillations in the phase qubit adiabatic measurement. The voltage gain and the amplifier noise temperature are calculated. We simulate the preparation of a generalized Bell state and compute the relaxation times required for achieving high fidelities. We consider two capacitively coupled phase qubits similar to that used in the experimental work of R. Bialczak et al. (Nature Physics, 6, 409, 2010). The Bell state was created using a NOT gate and a universal entangling gate. We solved the equation of motion for the density matrix with the Bloch relaxation times, T{sub 1} and T{sub 2}. For every qubit we took into consideration all the states in the shallow well including the states outside the qubit manifold. Also we took into consideration unwanted interaction between the qubits during the application of the NOT gate. The NOT gate was implemented using a Gaussian pulse assuming the frequency difference between the two qubits is 200 MHz. An entangling gate was implemented reducing this frequency difference to zero. We have found the optimal parameters for the Gaussian pulse and the optimal duration for the entangling gate. We have shown that the maximum fidelity of 0.99 can be achieved for the minimum relaxation time, T{sub 1} = 1.2 {micro}s, if T{sub 2} = 2T{sub 1}. By slightly increasing the required value of T{sub 1}, one can sharply reduce the required value for T{sub 2}.
ABSTRACT We report a systematic, measurement-induced irreversibility in superconducting quantum circuits that is not accounted for by any tested conventional noise model. Using IBM Quantum processors (ibm_marrakesh and ibm_kingston), we implement a time-reversal protocol in which mid-circuit measurements are inserted between a unitary U and its inverse U†. The fidelity deficit ΔF = F(dummy) − F(meas) grows linearly with measurement count M, reaching ΔF = 0.235 (22.2σ) and ΔF = 0.164 (24.0σ) at M = 8 on the two processors. Three independent controls rule out conventional noise sources: (1) T-independence of the spectator-qubit phase shift (dA ≈ +0.10 at T = 40 and 80 μs) eliminates crosstalk and leakage; (2) a non-Markovian symmetry test (spread = 1.5σ) eliminates decoherence asymmetry; and (3) cross-backend reproducibility of the linear ΔF(M) scaling eliminates hardware-specific measurement noise. The three observations share a common structural feature: the irreversibility is tied to discrete measurement events rather than free-evolution time, accumulates proportionally to their count, and reproduces across independent hardware. We report these observations as experimental evidence consistent with the interpretation that the imaginary unit i in the Schrödinger equation reflects a physically real internal structure of time, and that quantum measurement drives an irreversible projection of that structure onto the real axis. This interpretation is developed from first principles in Sec. II and connected to an existing theoretical framework [13] in Sec. VI. Keywordsquantum computing, mid-circuit measurement, complex time, irreversibility, IBM Quantum, time-reversal protocol
This document fixes, before the data exist, the hypothesis, apparatus, observables, cadence, analysis, thresholds, controls, stopping rule and reporting commitment of a one-year search for a modulation of superconducting-qubit energy relaxation (T1) at the sidereal frequency, 1/(23 h 56 m 4.09 s), beyond what the solar day and its seasonal modulation can produce. Data collection began on 17 October 2026 at 16:42 UTC on qubit 9 of the IBM Heron processor ibm_fez: an eight-delay inversion-recovery T1 measurement every six hours (about 3 s of processor time each), with the device's calibration values polled hourly. The analysis is fixed in advance: a least-squares fit of a smooth drift plus sinusoids at the solar, sidereal, anti-sidereal and extended-sidereal frequencies, with the reported amplitude leakage-corrected as sqrt(A_sid^2 - A_anti^2) (Farley and Storey 1954). The pipeline was validated on synthetic data before the first measurement and recovers an injected 0.3% at 2.7-3.4 sigma while returning 0.5 sigma with nothing injected. Detection requires a leakage-corrected amplitude at or above 3 sigma, both control channels below 2 sigma, a phase stable between the two halves of the year, and survival when runs adjacent to calibrations are removed; otherwise the result is the 95% upper limit, expected near 0.3%. The search is declared inconclusive if fewer than 900 of 1460 scheduled runs succeed or the anti-sidereal control exceeds 3 sigma. An amplitude matching the known cosmic-ray anisotropy (~0.1%) is a calibration, not a discovery. Stopping rule: one year, with a six-month interim look at the controls only; a second year is pre-declared as the response to an inconclusive or 2-3 sigma outcome. The result will be reported whether it is a detection, a bound, or a failure of the apparatus. Standard physics predicts a null result at this sensitivity; the alternative hypothesis is from The Cosmic Page (doi:10.5281/zenodo.23287018, Ch. 13) and the research proposal doi:10.5281/zenodo.23201109. Included: the pre-registration (PDF and LaTeX source), the monitor script that runs on the device, the fixed analysis script, the synthetic-data validation script with its results and figure, and the README. First data point: job db9qap9gv2cc73e5tufg, 2026-10-17T16:42:19Z, T1 = 162.9 +/- 7.9 us.