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Summary of Duties and Responsibilities:
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.

Required Minimum Qualifications (for temps/postdocs only, delete for all other positions):
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.

Preferred Qualifications:
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 is highly desirable, as is 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). Direct experience with both NV centers and qubits is rare; strong expertise in one area and a clear commitment to mastering the other is expected.

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 is strongly preferred.

Experience with pulse-sequencing and control electronics (arbitrary waveform generators, FPGA-based quantum controllers, time taggers) and 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, and familiarity with what conventional characterization (transport, PPMS/MPMS, X-ray scattering, electron microscopy) reveals.

Demonstrated ability to communicate effectively in written reports, oral presentations, manuscripts, and interdisciplinary team discussions; collaborate with others; maintain accurate laboratory records; and meet project milestones.

Department/Program & College Description:
Would you like to work for a National Laboratory that conducts world-renowned research? Would you enjoy working on a beautiful university campus? Can you imagine yourself in a mid-sized location that regularly ranks as one of the U.S. Best Places to Live? If you answered yes to any of these questions, you should consider a career with Ames National Laboratory!

Ames Laboratory is a U.S. Department of Energy federally contracted National Laboratory located in Ames, Iowa, on the campus of Iowa State University. We are dedicated to translating foundational science through applied research to create technological innovations. We create materials, inspire minds to solve problems, and address some of the most challenging issues facing our world today. We promote and believe in a culture of civility and shared ownership in support of the Laboratory's collective success.

Department Unit/Website (if applicable):
www.ameslab.gov

Application Instructions:
To apply for this position, please click on “Apply” and complete the Employment Application. Please be prepared to enter or attach the following:

• Resume/Curriculum Vitae
• Letter of Application/Cover Letter
• List of Professional References

Why Choose Iowa State University?
Iowa State Employees enjoy comprehensive health and work-life benefits, including medical and dental, as well as:

• 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
• Iowa State offers WorkFlex options for some positions. WorkFlex offers flexibility on when, where, and how you do your work. For more information, please speak with the Hiring Manager.

If you have questions regarding this application process, please email [email protected], or call 515-294-4800 or Toll Free: 1-877-477-7485.

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Employees with appointment at Ames National Laboratory are subject to particular restrictions related to participation in Foreign Government Sponsored or Affiliated Activities, as defined and detailed in United States Department of Energy Order 486.1A. You will be asked to disclose any such participation during the recruitment phase for review by Ames National Laboratory.

Employment is contingent upon satisfying applicable requirements of Ames National Laboratory’s federal sponsor, the United States Department of Energy, and ISU requirements. These may include background checks and eligibility determinations related to access of facilities, information, or projects. This position requires the incumbent to obtain and maintain government access authorization for the duration of the appointment. 

Iowa State University does not discriminate on the basis of race, color, age, ethnicity, religion, national origin, pregnancy, sexual orientation, genetic information, sex, marital status, disability, or status as a U.S. Veteran. Inquiries regarding non-discrimination policies may be directed to Office of Equal Opportunity, 2680 Beardshear Hall, 515 Morrill Road, Ames, Iowa 50011, Tel. 515-294-7612, email [email protected].

General ISU compensation information can be found on the University Human Resources website. Please note that this is only a list of ranges and individuals will be paid commensurate with qualifications.