Weidner Group

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Dr Carrie Weidner
Lecturer in Quantum Engineering
Research interests and activities
I am interested broadly in the control and manipulation of quantum systems. I am originally trained as an experimental cold atom physicist, but since my PhD studies in JILA at the University of Colorado Boulder, my research has branched out substantially. While we still focus on atom-based systems, my main research foci are:
- Magnetic field imaging based on single-pixel imaging of the Faraday effect in hot atom vapour. Eventually we plan to use squeezed light generated by polarization self-rotation in the vapour to enhance the sensitivity of our magnetometers. This project is supported by the QuantIC imaging and sensing hub.

- Quantum-enhanced inertial sensing with ultracold atoms trapped in phase-modulated (or shaken) optical lattices. We hope to build a system capable of performing six-axis inertial sensing in a robust and tunable system. This work is supported by EPSRC, InnovateUK, and our industry partners Infleqtion, Inc.

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The generation of interesting quantum states in optical lattices via optimal control. We have recently shown that GKP states can be deterministically generated by controlling the wavefunction of atoms trapped in the individual sites of a very deep optical lattice.

In the above figure, (a) and (c) show ideal Wigner functions for the GKP states with 10 dB squeezing, and (b) and (d) show the optimized Wigner functions that can be obtained in an experimental system [note the data is simulation only, we are building the experiment now!].
- Robust quantum control. In collaboration with Profs. Edmond Jonckheere (emeritus, USC), Frank Langbein (Cardiff), and Sophie Schirmer (Swansea), I am working on the design, implementation, and analysis of robust quantum control protocols in practical quantum systems.
- Quantum physics education. I am broadly interested in graduate-level experimental physics training [in collaboration with Prof. Heather Lewandowski, JILA], as well as equity of access in quantum physics education through simulation tools and 3D-printable components for use in quantum demonstration tools and experiments.
I am also collaborating with others in QET Labs on atoms and integrated photonics [with Prof. Martin Cryan], quantum memories in hot and cold atom vapours [with Dr Alex Clark], and atomic systems for indefinite causality [with Dr Giulia Rubino].
Current postdocs and research fellows
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Vineet Bharti
Senior Research Associate
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Dhritiman Chakraborty
Research Associate
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Cyril Torre
Research Associate
Current PhD students
- Yolan Ankaine
- Deepak Bhardwaj
- Samuel Harding
- Meagan Hough
- Matthew Jones
- Harry Kendell
- Matthew Stafford
Major research topics
- Atomic physics
- Quantum sensing
- Robust quantum control
- Quantum simulation
- Quantum education research
Active grants
- 2024-29: co-WP-lead, QEPNT Hub, Weidner group will receive roughly £1m in funding
- Subcontractor, Innovated UK Quantum Navigation Systems Resilience Project (lead Infleqtion UK, Inc.), £216k awarded to Weidner group
- co-I, Quantum Information Science and Technology Centre for Doctoral Training (QIST CDT) between Universities of Bristol and Sussex
- PI, Robust, trapped ultracold atom interferometry for six-axis inertial sensing, £724k awarded (+£300k in in-kind funding from Infleqtion, Inc., 6/2023 start, 24 months), EPSRC
- PI, Magnetic Field Imaging with Squeezed Light in Hot Atom Vapour, QuantIC Accelerated Development Fund, £192k awarded (1/2023 start, 20 months)
Recent publications
- H.C.P. Kendell, G. Ferranti, C.A. Weidner. Deterministic generation of highly squeezed GKP states in ultracold atoms. APL Quantum. 1, 026109, (2024).
- Legrand, F.-R. Winkelmann, W. Alt, D. Meschede, A. Alberti, C.A. Weidner. Three-dimensional imaging of single atoms in an optical lattice via helical point-spread-function engineering. Phys. Rev. A 109 033304, (2024).
- Khalid, C.A. Weidner, E. Jonckheere, S.G. Schirmer, F.C. Langbein. Statistically Characterising Robustness and Fidelity of Quantum Controls and Quantum Control Algorithms. Phys. Rev. A 107, 032606, (2023).
- F.-R. Winkelmann, C.A. Weidner, G. Ramola, W. Alt, D. Meschede, A. Alberti. Direct measurement of the Wigner function of atoms in an optical trap. J. Phys. B: At. Mol. Opt. Phys., 55, 194004 (2022).
- Dalgaard, C.A. Weidner, F. Motzoi. Dynamical uncertainty propagation with noisy quantum parameters. Phys. Rev. Lett. 128, 150503, (2022).
- Zaman Ahmed, J.H.M. Jensen, C. Weidner, J.J. S{\o}rensen, M. Mudrich, J.F. Sherson. Quantum Composer: A programmable quantum visualization and simulation tool for education and research. Am. J. Phys. 89, 307, (2021).
- Elíasson, R. Heck, J.S. Laustsen, R. Müller, J.J. Arlt, C.A. Weidner, and J.F. Sherson. Spatial tomography of individual atoms in a quantum gas microscope. Phys. Rev. A 102, 053311, (2020).
- C.A. Weidner and D.Z. Anderson. Experimental demonstration of shaken lattice interferometry. Phys. Rev. Lett. 120, 263201, (2018).
Contact me
I am not currently recruiting PhD students, but anyone interested in working with my group should submit an application to the Bristol/Sussex QIST CDT or the DTP programme via the School of Physics and/or the School of Electrical, Electronic, and Mechanical Engineering (EEME) at the University of Bristol. I will consider strong applications for the autumn 2025 CDT and DTP intake.
Postdoctoral researchers interested in my group will need to bring their own funding, but I am willing to help support fellowship applications from strong candidates. Please contact me if you are interested in pursuing this scheme.