About

Monika Schleier-Smith is an Associate Professor in the Physics Department at Stanford University. She received her Ph.D. from the Massachusetts Institute of Technology in 2011, following undergraduate studies at Harvard University where she earned an A.B. in Chemistry & Physics and Mathematics in 2005. Her postdoctoral research was conducted at the LMU Munich and the Max Planck Institute of Quantum Optics. Her current research focuses on advancing optical control of interactions among laser-cooled atoms, with applications in quantum simulation, metrology, and computation. She has pioneered techniques and ideas for simulating phenomena of condensed-matter physics and quantum gravity using tools of atomic physics, and has developed protocols in quantum control for entanglement-enhanced sensing.

Research topics

• Computer Science
• Quantum mechanics
• Physics
• Geometry
• Atomic physics
• Computer architecture
• Condensed matter physics
• Theoretical physics
• Mathematics

Selected publications

• Interfacing Atomic Spins with Photons for Quantum Metrology, Simulation and Computation

  arXiv (Cornell University) · 2025-12-31

  preprintOpen access1st authorCorresponding

  These lecture notes discuss applications of atom-light interactions in cavities to quantum metrology, simulation, and computation. A focus is on nonlocally interacting spin systems realized by coupling many atoms to a delocalized mode of light. We will build up from the fundamentals: understanding how a cavity enables light to coherently imprint information on atoms and atoms to imprint information on the light, enabling quantum non-demolition measurements that constitute a powerful means of engineering nonclassical states. By extension, letting the intracavity light act back on the atoms enables coherent photon-mediated interactions. I start by discussing collective spin models, emphasizing applications in entanglement-enhanced metrology, before proceeding to richer many-body physics enabled by incorporating spatiotemporal control or employing multiple cavity modes. I will highlight opportunities for leveraging these tools for quantum simulations inspired by problems in condensed matter and quantum gravity. Along the way, I provide a pedagogical introduction to criteria for strong atom-light coupling, illustrate how the corresponding figure of merit -- the cooperativity -- sets fundamental limits on the coherence of atom-light interactions, and discuss prospects for harnessing high-cooperativity cavity QED in quantum simulation and computation.

  PublisherDOI

• Interfacing Atomic Spins with Photons for Quantum Metrology, Simulation and Computation

  ArXiv.org · 2025-12-31

  articleOpen access1st authorCorresponding

  These lecture notes discuss applications of atom-light interactions in cavities to quantum metrology, simulation, and computation. A focus is on nonlocally interacting spin systems realized by coupling many atoms to a delocalized mode of light. We will build up from the fundamentals: understanding how a cavity enables light to coherently imprint information on atoms and atoms to imprint information on the light, enabling quantum non-demolition measurements that constitute a powerful means of engineering nonclassical states. By extension, letting the intracavity light act back on the atoms enables coherent photon-mediated interactions. I start by discussing collective spin models, emphasizing applications in entanglement-enhanced metrology, before proceeding to richer many-body physics enabled by incorporating spatiotemporal control or employing multiple cavity modes. I will highlight opportunities for leveraging these tools for quantum simulations inspired by problems in condensed matter and quantum gravity. Along the way, I provide a pedagogical introduction to criteria for strong atom-light coupling, illustrate how the corresponding figure of merit -- the cooperativity -- sets fundamental limits on the coherence of atom-light interactions, and discuss prospects for harnessing high-cooperativity cavity QED in quantum simulation and computation.

  PublisherOA PDF

• Optically accessible high-finesse millimeter-wave resonator for cavity quantum electrodynamics with atom arrays

  ArXiv.org · 2025-06-06

  preprintOpen accessSenior author

  Cavity quantum electrodynamics (QED) is a powerful tool in quantum science, enabling preparation of non-classical states of light and scalable entanglement of many atoms coupled to a single field mode. While the most coherent atom-photon interactions have been achieved using superconducting millimeter-wave cavities coupled to Rydberg atoms, these platforms so far lack the optical access required for trapping and addressing individual atomic qubits. We present a millimeter-wave Fabry-Pérot cavity with finesse $5.8(1) \times 10^7$ at a temperature of 1 K providing generous transverse optical access (numerical aperture 0.56). Conflicting goals of strong atom-photon coupling and optical access motivate a near-confocal geometry. Close to confocality, however, post-paraxial corrections to the cavity spectrum introduce unexpected degeneracies between transverse modes, leading to excess cavity loss. Modeling these corrections allows for tuning the cavity geometry to evade this loss, producing a high finesse that will enable cavity QED experiments with trapped atoms deep in the strong coupling regime.

  PublisherOA PDFDOI

• Optically accessible high-finesse millimeter-wave resonator for cavity quantum electrodynamics with atom arrays

  Physical Review Applied · 2025-10-06 · 2 citations

  articleOpen accessSenior author

  Cavity quantum electrodynamics (QED) is a powerful tool in quantum science, enabling preparation of nonclassical states of light and scalable entanglement of many atoms coupled to a single field mode. While the most coherent atom-photon interactions have been achieved using superconducting millimeter-wave cavities coupled to Rydberg atoms, these platforms so far lack the optical access required for trapping and addressing individual atomic qubits. We present a millimeter-wave Fabry-Pérot cavity with finesse <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mn>5.8</a:mn><a:mo stretchy="false">(</a:mo><a:mn>1</a:mn><a:mo stretchy="false">)</a:mo><a:mo>×</a:mo><a:msup><a:mn>10</a:mn><a:mn>7</a:mn></a:msup></a:math> at a temperature of 1 K providing generous transverse optical access (numerical aperture 0.56). Conflicting goals of strong atom-photon coupling and optical access motivate a near-confocal geometry. Close to confocality, however, postparaxial corrections to the cavity spectrum introduce unexpected degeneracies between transverse modes, leading to excess cavity loss. Modeling these corrections allows for tuning the cavity geometry to evade this loss, producing a high finesse that will enable cavity QED experiments with trapped atoms deep in the strong coupling regime.

  PublisherDOI

• Entanglement-enhanced multiparameter sensing: leveraging cavity-mediated programmable interactions

  2025-03-19

  articleSenior author

  Entanglement is a powerful resource for improving the precision of quantum measurements. All-to-all entanglement that is naturally generated by long-range interactions in optical cavities is optimally suited to single parameter estimation tasks, such as timekeeping or sensing global fields. In our system, we combine global cavity-mediated interactions with local rotations to create multimode entangled states that are useful for a wider variety of quantum sensing tasks. As a specific example, we produce a two-mode squeezed state (EPR state). By treating one subsystem as a sensing region and the other as an ancilla or quantum memory, we achieve simultaneous sensitivity to displacements of two conjugate quadratures in the sensing region. Using an echo-based protocol, we simultaneously read out both quadratures with a sensitivity surpassing the local Heisenberg limit. This simultaneous sensitivity to conjugate displacements promises a provable speedup for sensing tasks such as characterizing bosonic random displacement channel. Our general method is scalable to larger and more complex graphs, laying groundwork for advanced quantum metrology protocols such as quantum compressed sensing.

  PublisherDOI

• Graph states of atomic ensembles engineered by photon-mediated entanglement

  Nature Physics · 2024-03-01 · 28 citations

  articleOpen accessSenior author

  Abstract Graph states are a broad family of entangled quantum states, each defined by a graph composed of edges representing the correlations between subsystems. Such states constitute versatile resources for quantum computation and quantum-enhanced measurement. Their generation and engineering require a high level of control over entanglement. Here we report on the generation of continuous-variable graph states of atomic spin ensembles, which form the nodes of the graph. We program the entanglement structure encoded in the graph edges by combining global photon-mediated interactions in an optical cavity with local spin rotations. By tuning the entanglement between two subsystems, we either localize correlations within each subsystem or enable Einstein–Podolsky–Rosen steering—a strong form of entanglement that enables the extraction of precise information from one subsystem through measurements on the other. We further engineer a four-mode square graph state, highlighting the flexibility of our approach. Our method is scalable to larger and more complex graphs, laying groundwork for measurement-based quantum computation and advanced protocols in quantum metrology.

  PublisherOA PDFDOI

• Spin Squeezing by Rydberg Dressing in an Array of Atomic Ensembles

  Physical Review Letters · 2023-08-10 · 56 citations

  articleOpen accessSenior author

  We report on the creation of an array of spin-squeezed ensembles of cesium atoms via Rydberg dressing, a technique that offers optical control over local interactions between neutral atoms. We optimize the coherence of the interactions by a stroboscopic dressing sequence that suppresses super-Poissonian loss. We thereby prepare squeezed states of $N=200$ atoms with a metrological squeezing parameter ${\ensuremath{\xi}}^{2}=0.77(9)$ quantifying the reduction in phase variance below the standard quantum limit. We realize metrological gain across three spatially separated ensembles in parallel, with the strength of squeezing controlled by the local intensity of the dressing light. Our method can be applied to enhance the precision of tests of fundamental physics based on arrays of atomic clocks and to enable quantum-enhanced imaging of electromagnetic fields.

  PublisherOA PDFDOI

• Degradation of Ta$_2$O$_5$ / SiO$_2$ Dielectric Cavity Mirrors in Ultra-High Vacuum

  arXiv (Cornell University) · 2023-08-31

  preprintOpen access

  In order for optical cavities to enable strong light-matter interactions for quantum metrology, networking, and scalability in quantum computing systems, their mirrors must have minimal losses. However, high-finesse dielectric cavity mirrors can degrade in ultra-high vacuum (UHV), increasing the challenges of upgrading to cavity-coupled quantum systems. We observe the optical degradation of high-finesse dielectric optical cavity mirrors after high-temperature UHV bake in the form of a substantial increase in surface roughness. We provide an explanation of the degradation through atomic force microscopy (AFM), X-ray fluorescence (XRF), selective wet etching, and optical measurements. We find the degradation is explained by oxygen reduction in Ta$_2$O$_5$ followed by growth of tantalum sub-oxide defects with height to width aspect ratios near ten. We discuss the dependence of mirror loss on surface roughness and finally give recommendations to avoid degradation to allow for quick adoption of cavity-coupled systems.

  PublisherOA PDFDOI

• Spin Squeezing by Rydberg Dressing in an Array of Atomic Ensembles

  PubMed · 2023-03-15 · 4 citations

  preprintOpen accessSenior author

  We report on the creation of an array of spin-squeezed ensembles of cesium atoms via Rydberg dressing, a technique that offers optical control over local interactions between neutral atoms. We optimize the coherence of the interactions by a stroboscopic dressing sequence that suppresses super-Poissonian loss. We thereby prepare squeezed states of N=200 atoms with a metrological squeezing parameter ξ^{2}=0.77(9) quantifying the reduction in phase variance below the standard quantum limit. We realize metrological gain across three spatially separated ensembles in parallel, with the strength of squeezing controlled by the local intensity of the dressing light. Our method can be applied to enhance the precision of tests of fundamental physics based on arrays of atomic clocks and to enable quantum-enhanced imaging of electromagnetic fields.

  PublisherOA PDFDOI

• Engineering Graph States of Atomic Ensembles by Photon-Mediated Entanglement

  Zenodo (CERN European Organization for Nuclear Research) · 2023-03-02

  datasetOpen accessSenior author

  This is data associated with the paper "Engineering Graph States of Atomic Ensembles by Photon-Mediated Entanglement" (arXiv).

  PublisherDOI

Recent grants

• Many-Particle Quantum Engineering with Photon-Mediated Interactions

  NSF · $457k · 2015–2018

• CAREER: Interfacing Spins with Photons - Quantum Many-Body Physics with Non-Local Interactions

  NSF · $839k · 2018–2024

Frequent coauthors

• Vladan Vuletić

  MIT-Harvard Center for Ultracold Atoms

  79 shared

• Ian D. Leroux

  66 shared

• Gregory Bentsen

  Brandeis University

  28 shared

• Emily J. Davis

  25 shared

• Avikar Periwal

  Stanford University

  20 shared

• Senka Ćuk

  Massachusetts Institute of Technology

  18 shared

• Eric S. Cooper

  Stanford University

  18 shared

• Jacob Hines

  Stanford University

  14 shared

Education

• Ph.D.

  Massachusetts Institute of Technology

• B.S.

  Harvard University