Research Topics

We are theory group that studies the interaction of electromagnetic fields with matter, from single atoms to mesoscopic solid-state objects, both in the classical and in the quantum regime.

Our current research efforts can be divided into the following four areas:

  1. Levitodynamics

  2. Macroscopic Quantum Superpositions

  3. Quantum Nano-Optics

  4. Quantum Magnonics

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Levitodynamics

Observing quantum phenomena requires to carefully isolate the system under study and
probe it with enormous precision. Levitation in ultra-high vacuum and control through electromagnetic forces is a promising method to meet these requirements. Following a top-down approach to quantum physics, we investigate how to bring large micrometer-sized objects to the quantum regime. Realizing coherent quantum dynamics of an object containing billions of atoms and its various degrees of freedom has implications for fundamental science and technological applications. Together with a rapidly growing number of laboratories around the globe, we are working to push the limits of our current abilities and understanding. Have a look at this quantum science seminar for an introduction to this exciting research field.

 

Group publications in Levitodynamics (chronological order)

Quantum Delocalization of a Levitated Nanoparticle
M. Rossi, A. Militaru, N. Carlon Zambon, A. Riera-Campeny, O. Romero-Isart, M. Frimmer, and L. Novotny
arXiv:2408.01264

Quantum Control of Continuous Systems via Nonharmonic Potential Modulation
P. T. Grochowski, H. Pichler, C. A. Regal, and O. Romero-Isart
arXiv:2311.16819

State Expansion of a Levitated Nanoparticle in a Dark Harmonic Potential
E. Bonvin, L. Devaud, M. Rossi, A. Militaru, L. Dania, D. S. Bykov, O. Romero-Isart, T. E. Northup, L. Novotny, and M. Frimmer
Phys. Rev. Lett. 132, 253602 (2024)

Cavity-mediated Long-range Interactions in Levitated Optomechanics
J. Vijayan, J. Piotrowski, C. Gonzalez-Ballestero, K. Weber, O. Romero-Isart, and L. Novotny
Nat. Phys. 19, 859 (2024)

Quantum Electrodynamics with a Nonmoving Dielectric Sphere: Quantizing Lorenz-Mie Scattering
P. Maurer, C. Gonzalez-Ballestero, and O. Romero-Isart
J. Opt. Soc. Am. B 40, 3137 (2023)

Quantum Theory of Light Interaction with a Lorenz-Mie Particle: Optical Detection and Three-Dimensional Ground-State Cooling
P. Maurer, C. Gonzalez-Ballestero, and O. Romero-Isart
Phys. Rev. A 108, 033714 (2023)

Levitated Optomechanics with Meta-Atoms
S. Lepeshov, N. Meyer, P. Maurer, O. Romero-Isart, and R. Quidant
Phys. Rev. Lett. 130, 233601 (2023)

Suppressing Recoil Heating in Levitated Optomechanics using Squeezed Light
C. Gonzalez-Ballestero, J. A. Zielińska, M. Rossi, A. Militaru, M. Frimmer, L. Novotny, P. Maurer, and O. Romero-Isart
PRX Quantum 4, 030331 (2023)

Simultaneous Ground-State Cooling of Two Mechanical Modes of a Levitated Nanoparticle
J. Piotrowski, D. Windey, J. Vijayan, C. Gonzalez-Ballestero, A. de los Ríos Sommer, N. Meyer, R. Quidant, O. Romero-Isart, R. Reimann, and L. Novotny
Nat. Phys. 19, 1009 (2023)

Interaction Between an Optically Levitated Nanoparticle and Its Thermal Image: Internal Thermometry via Displacement Sensing
T. Agrenius, C. Gonzalez-Ballestero, P. Maurer, and O. Romero-Isart
Phys. Rev. Lett. 130, 093601 (2023)

Spin-Controlled Quantum Interference of Levitated Nano Rotors
C. C. Rusconi, M. Perdriat, G. Hétet, O. Romero-Isart, and B. A. Stickler.
Phys. Rev. Lett. 129, 093605 (2022)

Time-of-Flight Quantum Tomography of Single Atom Motion
M. O. Brown, S. R. Muleady, W. J. Dworschack, R. J. Lewis-Swan, A. M. Rey, O. Romero-Isart, and C. A. Regal.
Nat. Phys. 19, 569 (2023)

Ponderomotive Squeezing of Light by a Levitated Nanoparticle in Free Space
A. Militaru, M. Rossi, F. Tebbenjohanns, O. Romero-Isart, M. Frimmer, and L. Novotny.
Phys. Rev. Lett. 129, 053602 (2022)

Mechanical Squeezing via Unstable Dynamics in a Microcavity
K. Kustura, C. Gonzalez-Ballestero, A. de los Ríos Sommer, N. Meyer, R. Quidant, and O. Romero-Isart.
Phys. Rev. Lett. 128, 143601 (2022) (See article talk)

Levitodynamics: Levitation and Control of Microscopic Objects in Vacuum
C. Gonzalez-Ballestero, M. Aspelmeyer, L. Novotny, R. Quidant, and O. Romero-Isart
Science 374, eabg3027 (2021)

Acoustic and Optical Properties of a Fast Spinning Dielectric Nanoparticle
D. Hümmer, R. Lampert, K. Kustura, P. Maurer, C. Gonzalez-Ballestero, O. Romero-Isart
Phys. Rev. B 101, 205416 (2020)

Single-Spin Magnetomechanics with Levitated Micromagnets
J. Gieseler, A. Kabcenell, E. Rosenfeld, J. D. Schaefer, A. Safira, M. J. Schuetz, C. Gonzalez-Ballestero, C. C. Rusconi, O. Romero-Isart, M. D. Lukin
Phys. Rev. Lett. 124, 163604 (2020)

Quantum Motional State Tomography with Non-Quadratic Potentials and Neural Networks
T. Weiss, O. Romero-Isart
Phys. Rev. Research 1, 033157 (2019)

Theory for Cavity Cooling of Levitated Nanoparticles via Coherent Scattering: Master Equation Approach
C. Gonzalez-Ballestero, P. Maurer, D. Windey, L. Novotny, R. Reimann, O. Romero-Isart
Phys. Rev. A 100, 013805 (2019)

Cavity-Based 3D Cooling of a Levitated Nanoparticle via Coherent Scattering
D. Windey, C. Gonzalez-Ballestero, P. Maurer, L. Novotny, O. Romero-Isart, R. Reimann
Phys. Rev. Lett. 122, 123601 (2019)

Quadratic Quantum Hamiltonians: General Canonical Transformation to a Normal Form
K. Kustura, C. C. Rusconi, O. Romero-Isart
Phys. Rev. A 99, 022130 (2019)

Internal Quantum Dynamics of a Nanoparticle in a Thermal Electromagnetic Field: a Minimal Model
A. Rubio López, C. Gonzalez-Ballestero, O. Romero-Isart
Phys. Rev. B 98, 155405 (2018)

Quantum Spin Stabilized Magnetic Levitation
C. C. Rusconi, V. Pöchhacker, K. Kustura, J. I. Cirac, O. Romero-Isart
Phys. Rev. Lett. 119, 167202 (2017)

Linear Stability Analysis of a Levitated Nanomagnet in a Static Magnetic Field: Quantum Spin Stabilized Magnetic Levitation
C. C. Rusconi, V. Pöchhacker, J. I. Cirac, O. Romero-Isart
Phys. Rev. B 96, 134419 (2017)

Ultrasensitive Inertial and Force Sensors with Diamagnetically Levitated Magnets
J. Prat-Camps, C. Teo, C. C. Rusconi, W. Wieczorek, O. Romero-Isart
Phys. Rev. Applied 8, 034002 (2017)

Near-field levitated quantum optomechanics with nanodiamonds
M. L. Juan, G. Molina-Terriza, T. Volz, O. Romero-Isart
Phys. Rev. A 94, 023841 (2016)

Magnetic Rigid Rotor in the Quantum Regime: Theoretical Toolbox
C. C. Rusconi, O. Romero-Isart
Phys. Rev. B 93, 054427 (2016)

Quantum Magnetomechanics with Levitating Superconducting Microspheres
O. Romero-Isart, L. Clemente, C. Navau, A. Sanchez, J. I. Cirac
Phys. Rev. Lett. 109, 147205 (2012)

Master-equation approach to optomechanics with arbitrary dielectrics
A. C. Pflanzer, O. Romero-Isart, J. I. Cirac
Phys. Rev. A 86, 013802 (2012)

Optically levitating dielectrics in the quantum regime: Theory and protocols
O. Romero-Isart, A. C. Pflanzer, M. L. Juan, R. Quidant, N. Kiesel, M. Aspelmeyer, J. I. Cirac
Phys. Rev. A 83, 013803 (2011)

Toward quantum superposition of living organisms
O. Romero-Isart, M. L. Juan, R. Quidant, J. I. Cirac
New J. Phys. 12, 033015 (2010)

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Macroscopic Quantum Superpositions

Do the laws of quantum physics hold for massive objects of arbitrary size? Our goal is to propose ambitious yet feasible experiments to prepare a massive object in a large quantum superposition state. This requires to design and optimize novel protocols while taking into account sources of decoherence and noise that are relevant to current experiments. Together with the experimental groups of M. Aspelmeyer, L. Novotny, and R. Quidant, we are addressing pursuing this goal within the project Q-Xtreme, which has been awarded with an ERC Synergy Grant 2020. The motivation and long-term goal of Q-Xtreme is to (i) test quantum mechanics in regimes where collapse models predict a breakdown of the superposition principle, (ii) establih a new generation of ultra-precise sensors, and (iii) open the door to exploring the interplay between quantum mechanics and gravity.

Group publications in Macroscopic Quantum Superpositions (chronological order)

Wigner Analysis of Particle Dynamics in Wide Nonharmonic Potentials
A. Riera-Campeny, M. Roda-Llordes, P. T. Grochowski,, and O. Romero-Isart
Quantum 8, 1393 (2024)

Numerical Simulation of Large-Scale Nonlinear Open Quantum Mechanics
M. Roda-Llordes, D. Candoli, P. T. Grochowski, A. Riera-Campeny, T. Agrenius, J. J. Garca-Ripoll, C. Gonzalez-Ballestero, and O. Romero-Isart
Phys. Rev. Research 6, 013262 (2024)

Macroscopic Quantum Superpositions in a Wide Double-Well Potential
M. Roda-Llordes, A. Riera-Campeny, D. Candoli, P. T. Grochowski, and O. Romero-Isart
Phys. Rev. Lett. 132, 023601 (2024)

Fast Quantum Interference of a Nanoparticle via Optical Potential Control
L. Neumeier, M. Ciampini, O. Romero-Isart, M. Aspelmeyer, and N. Kiesel
Proc. Natl. Acad. Sci. U.S.A. 121, e2306953121 (2024)

Large Quantum Delocalization of a Levitated Nanoparticle using Optimal Control: Applications for Force Sensing and Entangling via Weak Forces
T. Weiss, M. Roda-Llordes, E. Torrontegui, M. Aspelmeyer, O. Romero-Isart
Phys. Rev. Lett. 127, 023601 (2021) (See article talk)

On-chip quantum interference of a superconducting microsphere
H. Pino, J. Prat-Camps, K. Sinha, B. Venkatesh, O. Romero-Isart
Quantum Sci. Technol. 3, 25001 (2018)

Coherent Inflation for Large Quantum Superpositions of Microspheres
O. Romero-Isart
New J. Phys. 19, 123029 (2017)

Quantum superposition of massive objects and collapse models
O. Romero-Isart
Phys. Rev. A 84, 052121 (2011)

Large Quantum Superpositions and Interference of Massive Nanometer-Sized Objects
O. Romero-Isart, A. C. Pflanzer, F. Blaser, R. Kaltenbaek, N. Kiesel, M. Aspelmeyer, J. I. Cirac
Phys. Rev. Lett. 107, 020405 (2011)

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Quantum Nano-Optics

The properties of light and electromagnetic fields in general are profoundly altered near micro- or nanoscopic bodies. The unusual properties of electromagnetic radiation at the nanoscale enables scientists to forge photons into a precision tool for manipulating quantum systems, such as atoms and superconducting qubits. We strive to overcome current limits of control with new ideas built upon a deep understanding of underlying physical effects, both in the classical and quantum regime. For instance, we investigate nanophotonic traps for cold atoms and study novel ways to shape and utilize spatio-temporal features of electromagnetic fields.

Group publications in Quantum Nano-Optics (chronological order)

Spatial Addressing of Qubits in a Dispersive Waveguide
M. Zanner, R. Albert, E. I. Rosenthal, S. Casulleras, I. Yang, C. M. F. Schneider, O. Romero-Isart, and G. Kirchmair
arXiv:2407.10617

Probing Surface-Bound Atoms with Quantum Nanophotonics
D. Hümmer, O. Romero-Isart, A. Rauschenbeutel, P. Schneeweiss
Phys. Rev. Lett. 126, 163601 (2021) (See article talk)

Remote Individual Addressing of Quantum Emitters with Chirped Pulses
S. Casulleras, C. Gonzalez-Ballestero, P. Maurer, J. García-Ripoll, O. Romero-Isart
Phys. Rev. Lett. 126, 103602 (2021) (See article talk)

Radiation Reaction of a Jiggling Dipole in a Quantum Electromagnetic Field
A. E. Rubio López, O. Romero-Isart
Phys. Rev. Lett. 123, 243603 (2019)

Heating in Nanophotonic Traps for Cold Atoms
D. Hümmer, P. Schneeweiss, A. Rauschenbeutel, O. Romero-Isart
Phys. Rev. X 9, 041034 (2019)

Circumventing Magnetostatic Reciprocity: A Diode for Magnetic Fields
J. Prat-Camps, P. Maurer, G. Kirchmair, O. Romero-Isart
Phys. Rev. Lett. 121, 213903 (2018)

Cooperative Effects in Closely Packed Quantum Emitters with Collective Dephasing
B. Venkatesh, M. L. Juan, O. Romero-Isart
Phys. Rev. Lett. 120, 033602 (2018)

Ultrafocused Electromagnetic Field Pulses with a Hollow Cylindrical Waveguide
P. Maurer, J. Prat-Camps, J. I. Cirac, T. W. Hänsch, O. Romero-Isart
Phys. Rev. Lett. 119, 043904 (2017)

Ultrashort Pulses for Far-Field Nanoscopy
P. Maurer, J. I. Cirac, O. Romero-Isart
Phys. Rev. Lett. 117, 103602 (2016)

Long-Distance Transfer and Routing of Static Magnetic Fields
C. Navau, J. Prat-Camps, O. Romero-Isart, J. I. Cirac, A. Sanchez
Phys. Rev. Lett. 112, 253901 (2014)

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Quantum Magnonics

The internal complexity and quantum origin of magnetism is still an intense research topic. Spin waves, namely collective magnetic excitations in ferromagnets, are specially interesting as their complex properties are ideal for classical information processing and for quantum technologies. These properties include externally tuneable dispersion relations, large nonlinearities, much lower losses than electronic currents, and the capacity to interact with any other degree of freedom. We focus on proposing applications in information processing, magnetic sensing, and quantum technologies sing spin waves and their quanta, magnons.

Group publications in Quantum Magnonics (chronological order)

Strongly Coupled Spin Waves and Surface Acoustic Waves at Room Temperature
Y. Hwang, J. Puebla, K. Kondou, C. Gonzalez-Ballestero, H. Isshiki, C. Sánchez Muñoz, L. Liao, F. Chen, W. Luo, S. Maekawa, and Y. Otani
Phys. Rev. Lett. 132, 056704 (2024)

Generation of Spin-Wave Pulses by Inverse Design
S. Casulleras, S. Knauer, Q. Wang, O. Romero-Isart, A. V. Chumak, and C. Gonzalez-Ballestero
Phys. Rev. Applied 19, 064085 (2023)

Quantum Interfaces between Magnons and Paramagnetic Spins
C. Gonzalez-Ballestero, O. Romero-Isart
In Advances in Magnetics Roadmap on Spin-Wave Computing
IEEE Transactions on Magnetics 58, 0800172 (2022)

Towards a Quantum Interface between Spin Waves and Paramagnetic Spin Baths
C. Gonzalez-Ballestero, T. van der Sar, O. Romero-Isart
Phys. Rev. B 105, 075410 (2022) (See article talk)

Quantum Size Effects in the Magnetic Susceptibility of a Metallic Nanoparticle
M. Roda-Llordes, C. Gonzalez-Ballestero, A. E. Rubio López, M. Martínez-Pérez, F. Luis, O. Romero-Isart
Phys. Rev. B 104, L100407 (2021) (See article talk)

Effective Quantum Dynamics Induced by a Driven Two-Level System Bath
K. Kustura, O. Romero-Isart, C. Gonzalez-Ballestero
Phys. Rev. A 103, 053709 (2021) (See article talk)

Quantum Acoustomechanics with a Micromagnet
C. Gonzalez-Ballestero, J. Gieseler, O. Romero-Isart
Phys. Rev. Lett. 124, 093602 (2020)

Theory of Quantum Acoustomagnonics and Acoustomechanics with a Micromagnet
C. Gonzalez-Ballestero, D. Hümmer, J. Gieseler, O. Romero-Isart
Phys. Rev. B 101, 125404 (2020)

Hybrid Architecture for Engineering Magnonic Quantum Networks
C. C. Rusconi, M. J. Schuetz, J. Gieseler, M. Lukin, O. Romero-Isart
Phys. Rev. A 100, 022343 (2019)