Postdoctoral Research Associate - Ames National Laboratory

Iowa State University • Ames, IA

5d • Onsite

About The Position

The Division of Materials Science and Engineering at Ames National Laboratory seeks a Postdoctoral Research Associate to conduct experimental research on measurements and understanding the microscopic origins of low-frequency (1/f) magnetic and electric noise in superconducting quantum circuits, with particular focus on transmon qubits. The primary experimental tool will be quantum sensing with nitrogen-vacancy (NV) centers in diamond, used as local, magnetically selective passive probes of the noise environment at the surfaces, interfaces, and thin films from which superconducting devices are built. The central research goal is to identify which physical mechanisms – surface and interface spins, magnetic defects, two-level systems, trapped flux and vortex motion, and nonequilibrium quasiparticles – generate the 1/f flux and charge noise that limits qubit coherence, and to determine what fraction of a qubit’s decoherence is magnetic in origin. This will be achieved by combining NV-based noise spectroscopy (spin relaxometry and dynamical-decoupling measurements of T1 and T2) and static-field ODMR magnetometry with standard transmon characterization and qubit-intrinsic noise spectroscopy (CPMG and spin-locking sequences) on the same devices, in the same cryostat and cooldown. The postdoctoral researcher will play a key role in commissioning a new cryogen-free dilution-refrigerator platform that integrates confocal optical access and NV positioning with filtered microwave wiring for qubit control and dispersive readout. Specific tasks include optimizing diamond sensor geometry, NV depth and NV-to-device standoff; developing pulse sequences, measurement protocols and analysis pipelines; and devising strategies that isolate the qubit from the optical and microwave excitation used for NV readout, including systematic characterization of light-induced quasiparticle effects. The work will complement the group’s established tunnel-diode resonator quasiparticle spectroscopy. The work will include planning and conducting experiments, critically analyzing measured noise spectra and modeling them in terms of microscopic fluctuator ensembles, and performing numerical calculations or simulations where appropriate. The researcher must be able to work both independently and collaboratively and to communicate effectively across condensed-matter physics, materials science, quantum sensing, and quantum information science.

Requirements

• Ph.D. in experimental condensed-matter physics, applied physics, quantum science and engineering, atomic, molecular and optical physics, materials science and engineering, or a closely related field.

Nice To Haves

• Hands-on experience with NV centers in diamond or other optically addressable spin defects, including optically detected magnetic resonance (ODMR), pulsed microwave spin control, confocal microscopy, and single-photon detection.
• Experience with shallow NV ensembles, near-surface sensing, T1 relaxometry or dynamical-decoupling noise spectroscopy.
• NV magnetometry of superconducting or magnetic materials.
• Solid understanding of noise physics and quantum noise spectroscopy: power spectral densities, filter-function analysis of pulse sequences, the fluctuation–dissipation relation, and microscopic models of 1/f flux and charge noise (surface spins, two-level systems, trapped vortices).
• Experience with superconducting qubits or high-Q superconducting resonators, including packaging, cryogenic microwave wiring, attenuation and filtering, dispersive readout, and coherence measurements (T1, Ramsey, echo, CPMG).
• Strong expertise in NV centers or qubits and a clear commitment to mastering the other.
• Demonstrated hands-on experience with low-temperature experimental techniques, cryogenic systems, vacuum equipment, magnetic fields and magnetic shielding, low-noise electronics, and precision measurements.
• Experience with dilution refrigerators, millikelvin measurements, and cryogenic optics.
• Experience with pulse-sequencing and control electronics (arbitrary waveform generators, FPGA-based quantum controllers, time taggers).
• Experience with scientific programming, quantitative data analysis, and simulation using tools such as Python, LabVIEW, MATLAB, Mathematica, Origin, or COMSOL Multiphysics.
• Background in superconductivity, magnetism, thin films, surfaces and interfaces, and effects of disorder.
• Familiarity with conventional characterization (transport, PPMS/MPMS, X-ray scattering, electron microscopy).
• Demonstrated ability to communicate effectively in written reports, oral presentations, manuscripts, and interdisciplinary team discussions.
• Ability to collaborate with others.
• Ability to maintain accurate laboratory records.
• Ability to meet project milestones.

Responsibilities

• Conduct experimental research on measurements and understanding the microscopic origins of low-frequency (1/f) magnetic and electric noise in superconducting quantum circuits.
• Use quantum sensing with nitrogen-vacancy (NV) centers in diamond as local, magnetically selective passive probes of the noise environment.
• Identify physical mechanisms generating 1/f flux and charge noise that limits qubit coherence.
• Determine the fraction of a qubit’s decoherence that is magnetic in origin.
• Combine NV-based noise spectroscopy and static-field ODMR magnetometry with standard transmon characterization and qubit-intrinsic noise spectroscopy.
• Play a key role in commissioning a new cryogen-free dilution-refrigerator platform.
• Optimize diamond sensor geometry, NV depth and NV-to-device standoff.
• Develop pulse sequences, measurement protocols and analysis pipelines.
• Devise strategies that isolate the qubit from optical and microwave excitation used for NV readout.
• Systematically characterize light-induced quasiparticle effects.
• Plan and conduct experiments.
• Critically analyze measured noise spectra and model them in terms of microscopic fluctuator ensembles.
• Perform numerical calculations or simulations where appropriate.
• Work both independently and collaboratively.
• Communicate effectively across condensed-matter physics, materials science, quantum sensing, and quantum information science.

Benefits

• Comprehensive health and work-life benefits, including medical and dental
• Retirement benefits including defined benefit and defined contribution plans
• Generous vacation, holiday, and sick time and leave plans
• Onsite childcare (Ames, Iowa)
• Life insurance and long-term disability
• Flexible Spending Accounts
• Various voluntary benefits and discounts
• Employee Assistance Program
• Wellbeing program
• WorkFlex options for some positions

What This Job Offers

• Job Type: Full-time
• Career Level: Entry Level
• Education Level: Ph.D. or professional degree