Anne-Marie Valente-Feliciano

RF-Budgeted Frame Compilation for Frequency-Multiplexed Superconducting-Qubit Control Using Qubit-Control Identity Records and a Circuit-Informed RFSoC Model

  1. Mingqi Ge,
  2. and Anne-Marie Valente-Feliciano
Frequency-multiplexed superconducting-qubit control requires more than carrier assignment: the RF budget of a shared source can perturb multi-qubit rotations through finite bandwidth,
crest factor, clipping, quantization, jitter, spurs, compression, crosstalk, and leakage. We present an RF-budgeted frame-compilation and validation workflow that combines qubit-control identity (QID) records, a MATLAB/Simulink-based circuit-informed RFSoC source-chain model, QuTiP qutrit dynamics, and Qiskit-derived algorithm workloads. QID records encode qubit-specific computational and leakage transition frequencies, pulse parameters, and drive-scale calibration, while the RF-chain profile and effective crosstalk-coupling matrix are provided as separate compiler inputs. Candidate multitone RF frames are scheduled under RF-budget constraints, propagated through the RFSoC model, decoded into computational and leakage transition frames, and evaluated in QuTiP for rotation error, leakage-aware fidelity, computational-subspace survival, and transient leakage. The studies progress from single-qutrit pulse closure to pairwise coexistence, multitone RF-frame capacity, and Bernstein-Vazirani (BV) and QAOA microwave layers extracted from Qiskit circuits. The simulations show that longer pulses improve per-frame aggregation but do not necessarily minimize time-normalized layer cost; clustered frequency maps, larger rotations, and multitone leakage stacking tighten closure. Under the nominal RF budget, a Qiskit-derived 12-qubit BV -Y90 layer closes in three validated four-tone frames at 240 ns, while QAOA mixer partitions vary with rotation angle and pulse duration. All reported results are model-based, decoherence-free simulation diagnostics rather than measured hardware fidelities or wiring-reduction claims.
arxiv pdf

Investigation of coherence of niobium-based resonators enabled by a fast-sealing microwave cavity

  1. Chi Zhang,
  2. Richard Germond,
  3. Noah Janzen,
  4. Anne-Marie Valente-Feliciano,
  5. Mustafa Bal,
  6. and Adrian Lupascu
Resonators and qubits with a niobium (Nb) base metal layer achieve some of the highest coherence times in superconducting quantum devices. The performance of such devices is often limited
by loss associated with two-level systems, which are found primarily at material surfaces and interfaces. The metal-air (MA) interface is a major contributor to device loss. In this work, we develop a fast-sealing microwave cavity that enables devices to be placed under vacuum within five minutes of oxide removal, thereby significantly reducing the MA interface loss compared to common device processing and packaging approaches. Using coplanar stripline resonators, we demonstrate that devices sealed in such a cavity exhibit internal quality factors exceeding one million at single-photon power. After re-exposure to air, the devices show downward resonance frequency shifts and quality factor degradations, quantitatively consistent with a model of Nb oxide regrowth. The fast-sealing microwave cavity provides a practical and consistent method to mitigate MA interface loss and sustain high coherence in Nb devices, and establishes a controlled platform for studying metal oxide regrowth kinetics and dielectric properties, the understanding of which is critical to achieving high coherence in superconducting quantum devices.
arxiv pdf