Cindy Regal

Micromechanical membranes can be quiet frequency sensors even at high amplitude

Cindy Regal — Sat, 21 Mar 2026 18:09:09 +0000

Micromechanical membranes can be quiet frequency sensors even at high amplitude Cindy Regal Sat, 03/21/2026 - 12:09

In our work published in NanoLetters, we develop an experimentally straightforward method to evade this tradeoff. Using a patterned, trampoline-shaped membrane, we find that dual-mechanical-mode operation can bring these sensors to a thermally-limited frequency stability. By measuring and correcting for frequency noise arising at high amplitude, we maintain this high stability when operating beyond the linear regime, opening new opportunities for membrane frequency sensing.

Drum-like membrane resonators are intriguing for precision sensing because their resonance frequencies can be sensitive to a variety of parameters of interest, from mass to thermal radiation. The quest for improved sensitivity in tensioned membranes faces a tradeoff in which a high amplitude of mechanical motion improves signal-to-noise, but too high of a drive (beyond the so-called critical amplitude) introduces nonlinear effects.

In our work published in NanoLetters, we develop an experimentally straightforward method to evade this tradeoff. Using a patterned, trampoline-shaped membrane, we find that dual-mechanical-mode operation can bring these sensors to a thermally-limited frequency stability. By measuring and correcting for frequency noise arising at high amplitude, we maintain this high stability when operating beyond the linear regime, opening new opportunities for membrane frequency sensing.

Off

Traditional

White

JILA Joins DOE’s Quantum Systems Accelerator for Next Phase of Quantum Innovation

Steven Burrows — Tue, 04 Nov 2025 19:18:36 +0000

JILA Joins DOE’s Quantum Systems Accelerator for Next Phase of Quantum Innovation Steven Burrows Tue, 11/04/2025 - 12:18

Steven Burrows / JILA Science Communications Manager

A round glass cell (centre, in black frame) is designed to hold a gas of molecules cooled to 50 billionths of a Kelvin. Credit: Ye Group/Steven Burrows/JILA

The U.S. Department of Energy (DOE) has announced a $625 million investment to advance the next phase of the National Quantum Information Science Research Centers, a cornerstone of the National Quantum Initiative. This funding will support five centers dedicated to accelerating quantum technologies that promise transformative impacts on science, industry, and national security.

Among these centers, the Quantum Systems Accelerator (QSA)—led by Lawrence Berkeley National Laboratory—will continue its mission to develop practical quantum systems that can solve real-world problems. QSA brings together leading institutions to tackle challenges in quantum computing, sensing, and networking, aiming to bridge the gap between theoretical advances and deployable technologies.

JILA is proud to remain a key partner in QSA through the Q-SEnSE Institute, which focuses on quantum sensing and precision measurement. These capabilities are essential for applications ranging from navigation and timing to probing fundamental physics. JILA Fellow Jun Ye will lead the JILA effort, supported by senior investigators and JILA Fellows Cindy Regal, Adam Kaufman, Ana Maria Rey, James Thompson, Murray Holland, and Xun Gao—a team internationally recognized for pioneering work in quantum optics, atomic physics, and many-body systems.

“JILA is proud to remain a key partner in QSA. Through our work in both QSA and Q-SEnSE, JILA plays a leading role in advancing quantum innovations at the national and international levels,” remarked Inese Berzina-Pitcher, Executive Director for Q-SEnSE.

The next five years of QSA will focus on building scalable quantum platforms, advancing error correction, and integrating quantum devices into scientific workflows. JILA’s expertise in ultracold atoms, optical lattices, and quantum simulation will play a critical role in these goals.

For more details, read the official announcements:

Energy Department Announces $625 Million to Advance the Next Phase of National Quantum Information Science Research Centers

The Quantum Systems Accelerator Embarks on Next Five Years of Pioneering Quantum Technologies for Science

Off

Traditional

White

Happy Birthday Quantum Mechanics! - Helgoland 2025

Steven Burrows — Mon, 14 Jul 2025 19:40:01 +0000

Happy Birthday Quantum Mechanics! - Helgoland 2025 Steven Burrows Mon, 07/14/2025 - 13:40

Physicists descended on the island of Helgoland this June to celebrate 100 years of quantum mechanics. Our group enjoyed contributing to this the convergence of quantum applications and foundations.

Off

Traditional

White

Cryogenic optical tweezer array

Steven Burrows — Wed, 28 May 2025 19:39:20 +0000

Cryogenic optical tweezer array Steven Burrows Wed, 05/28/2025 - 13:39

Our work on high optical access cryogenic system for Rydberg atoms has been published in PRX Quantum - see this viewpoint on our studies.

Off

Traditional

White

Cindy Regal Named 2025 Brown Investigator for Pioneering Quantum Research

Steven Burrows — Mon, 19 May 2025 15:53:56 +0000

Cindy Regal Named 2025 Brown Investigator for Pioneering Quantum Research Steven Burrows Mon, 05/19/2025 - 09:53

Steven Burrows / JILA Science Communications Manager

Cindy Regal in her lab.

Cindy Regal, University of Colorado Boulder Physics Professor and Baur-SPIE Chair at JILA, has been named a 2025 Brown Investigator by the Brown Institute for Basic Sciences at Caltech.

The Brown Institute for Basic Sciences was established in 2023 through a transformative $400 million gift from Caltech alumnus Ross M. Brown. The institute supports fundamental research with the potential to seed long-term breakthroughs in chemistry and physics.

"Mid-career faculty are at a time in their careers when they are poised and prepared to make profound contributions to their fields," Brown says, "My continuing hope is that the resources provided by the Brown Investigator Awards will allow them to pursue riskier innovative ideas that extend beyond their existing research efforts and align with new or developing passions, especially during this time of funding uncertainty."

Regal is one of eight recipients selected this year, and she will receive up to $2 million over five years to support her groundbreaking work in quantum physics.

She aims to use the research support to demonstrate quantum entanglement—a connection between particles like photons or atoms that persists despite their physical distance—with objects of larger mass than have been entangled before.

Regal said the Brown Investigator Award is a thrilling opportunity for her research group. “The Brown Institute’s focus on fundamental and risky studies will allow us to explore quantum mechanical phenomena in a regime that is enticing to physicists and for future impact, yet also exceedingly difficult to achieve in the laboratory,” she said, adding:

“We are keen to try a new concept in precision optical measurement and control that we hypothesize will generate quantum states in ever-larger and more tangible mechanical excitations. These explorations would not be possible to embark on without the unique resources provided to Brown Investigators.”

Regal joins a distinguished cohort of scientists from institutions including Princeton, Cornell, and the University of Chicago. Her selection underscores JILA’s continued leadership in quantum science and its commitment to advancing knowledge at the frontiers of physics.

Professor Cindy Regal, Baur-SPIE Chair at JILA, has been named a 2025 Brown Investigator by the Brown Institute for Basic Sciences at Caltech.

Off

Traditional

White

Quantum Billiard Balls: Digging Deeper into Light-Assisted Atomic Collisions

Steven Burrows — Tue, 18 Feb 2025 19:52:37 +0000

Quantum Billiard Balls: Digging Deeper into Light-Assisted Atomic Collisions Steven Burrows Tue, 02/18/2025 - 12:52

Kenna Hughes-Castleberry / JILA Science Communicator

When atoms collide, their exact structure—for example, the number of electrons they have or even the quantum spin of their nuclei—has a lot to say about how they bounce off each other. This is especially true for atoms cooled to near-zero Kelvin, where quantum mechanical effects give rise to unexpected phenomena. Collisions of these cold atoms can sometimes be caused by incoming laser light, resulting in the colliding atom-pair forming a short-lived molecular state before disassociating and releasing an enormous amount of energy. These so-called light-assisted collisions, which can happen very quickly, impact a broad range of quantum science applications, yet many details of the underlying mechanisms are not well understood.

In a new study published in Physical Review Letters, JILA Fellow and University of Colorado Boulder physics professor Cindy Regal, along with former JILA Associate Fellow Jose D’Incao (currently an assistant professor of physics at the University of Massachusetts, Boston) and their teams developed new experimental and theoretical techniques for studying the rates at which light-assisted collisions occur in the presence of small atomic energy splittings. Their results rely upon optical tweezers—focused lasers capable of trapping individual atoms—that the team used to isolate and study the products of individual pairs of atoms.

Their research offers new insights into how these special atomic collisions occur, helping to address the challenge of controlling atoms more effectively for applications in emulating quantum systems using arrays of atoms and even molecules.

A Collision Puzzle

As physicists work to improve control over atoms in optical tweezer experiments, JILA graduate student Steven Pampel, the paper’s first author, wanted to better understand how the rate at which light-assisted collisions occur changes under a range of circumstances. Light can create a wild array of outcomes, depending mostly on its frequency with respect to atomic transitions.

Exploiting the hyperfine structure in repulsive light-assisted collisions (LAC) on a 87-Rubidium atom pair in an optical tweezer. Image credit: Steven Burrows / JILA

“Light-assisted collisions can generate large amounts of energy compared to what is often tolerated in the world of ultracold atomic gases,” Regal elaborates. “This energy is imparted to the colliding atoms, which can be considered bad as they are large enough to cause atoms to escape from typical traps. But these collisions can also be useful when that energy can be controlled.”

In fact, the Regal group and other groups worldwide have previously used this energy to study how to load atoms into optical tweezers. However, a more comprehensive theoretical understanding of the collision process leading to such energy release was hard to come by, especially when considering atomic hyperfine structure—small energy shifts resulting from the coupling between an atom's nuclear spin and angular momentum from the atom’s electrons.

The basic model for light-assisted collisions has been understood for decades. In fact, the go-to model was developed by JILA Fellow Allan Gallagher and collaborator Prof. David Pritchard of MIT. But until recently, our understanding of light-assisted collisions came from very large optical traps that contain millions of atoms where the same light that confines the atoms also drives collisions, limiting control over the frequency of the light and information someone could obtain.

A Split Shot in a Game of Quantum Billiards

To determine how fast the collisions occur, the researchers in Regal’s laboratory began their experiment by preparing exactly two rubidium atoms in an optical tweezer. To accomplish this, the team harnessed a technique where single atoms are loaded into two separate optical tweezers and then the atoms are merged into a single optical trap. After merging, a carefully controlled pulse of laser light was applied to drive collisions between the two atoms.

This collisional laser light excites the atoms, creating a quantum superposition state where either atom could have absorbed a photon, but it is unclear which one. In this state, electronic forces act at much larger distances than they otherwise would and give the atoms such a large amount of kinetic energy that they escape the trap. In this game of “quantum billiard balls”, the photon is like the cue ball that smashes into two other balls (the atoms) simultaneously, sending them flying off the table.

The team then varied the frequency of the collisional light, i.e., the energy of the photon “cue”, and measured how quickly atom-pairs escaped the optical tweezer.

“We set the laser at a certain frequency, then varied the duration of the collisional light to see how many atoms remained in the trap,” Pampel adds. “From this, we could determine how quickly the atoms collided and gained enough energy to escape. By repeating this process at different frequencies, we could map out the influence of hyperfine structure in these collisions.”

This process allowed the researchers to measure the loss rates of the atoms quantitatively and in relation to the hyperfine effects, something that had never been done before.

New Imaging Methods and Quasi-Molecular States

During the experiments, the team developed a novel imaging technique to accurately determine if both atoms remained in the trap after a collision. This technique was crucial because standard imaging methods in optical tweezers would inadvertently kick both atoms out of the trap during the collision, making it impossible to tell whether the collisional light or the imaging light kicked out the atoms.

“We came up with a method that uses a special type of light-assisted collisions where only one atom gets kicked out most of the time,” Pampel explains. “This allowed us to identify the presence of two atoms by detecting a single atom. This mechanism is commonly used for loading single atoms in tweezers, but we showed it can be used in a more controlled setting for two-atom detection purposes as well.”

The researchers also developed a theoretical model to understand their experimental results, particularly why setting the light frequency to be close to that of certain hyperfine states resulted in different rates than other hyperfine states.

“Mapping out the potential energy curves for two colliding atoms in the presence of light and the hyperfine interaction required more complex analysis than previous works that had only taken into account the atomic fine structure¬—the interaction between electron’s spin and angular momentum,” D’Incao says.

“In addition, we built a collisional model that allows us to gain a better understanding of how the many hyperfine-dependent molecular states give rise to collision rates and the amount of energy released,” Pampel adds. This model could also be extended beyond rubidium atoms, helping to predict how other atomic elements might behave in similar situations.

Pushing Towards Precision

Beyond shedding new light on a long-standing puzzle, these findings could influence various endeavors with trapped neutral atoms such as quantum computing, metrology, and many-body physics, where controlling atomic collisions is essential for success. The ability to predict how atomic collisions will behave based on their hyperfine structure will likely be useful for advancing laser-cooling techniques, molecular quantum science, and the next generation of quantum-based technologies.

This research was supported by the Office of Naval Research, the National Science Foundation, the Department of Energy, the Quantum Systems Accelerator and the Swiss National Science Foundation.

In a new study published in Physical Review Letters, JILA Fellow and University of Colorado Boulder physics professor Cindy Regal, along with former JILA Associate Fellow Jose D’Incao (currently an assistant professor of physics at the University of Massachusetts, Boston) and their teams developed new experimental and theoretical techniques for studying the rates at which light-assisted collisions occur in the presence of small atomic energy splittings. Their results rely upon optical tweezers—focused lasers capable of trapping individual atoms—that the team used to isolate and study the products of individual pairs of atoms.

Off

Traditional

White

Tracking Magnetic Field Directions Using Tiny Atomic Compasses

Steven Burrows — Mon, 17 Feb 2025 19:57:01 +0000

Tracking Magnetic Field Directions Using Tiny Atomic Compasses Steven Burrows Mon, 02/17/2025 - 12:57

Kenna Hughes-Castleberry / JILA Science Communicator

Researchers at the University of Colorado Boulder have developed a novel method to measure magnetic field orientations using atoms as minuscule compasses. The research, a collaboration between JILA Fellow and ��Ҵ�ý�ƽ�� physics professor Cindy Regal and Svenja Knappe, a research professor in the Paul M. Rady Department of Mechanical Engineering, was recently published as the cover article in the journal Optica.

Off

Traditional

White

JILA and University of Colorado Boulder Awarded $20 million to Build a new "Quantum Machine Shop"

Steven Burrows — Fri, 21 Jun 2024 19:36:07 +0000

JILA and University of Colorado Boulder Awarded $20 million to Build a new "Quantum Machine Shop" Steven Burrows Fri, 06/21/2024 - 13:36

Kenna Hughes-Castleberry / JILA Science Communicator

From left to right, Aju Jugessur, Juliet Gopinath, Scott Diddams and Cindy Regal, who will lead the realization of a new facility at ��Ҵ�ý�ƽ��, with JILA's collaboration, for making nano devices. Credit: Patrick Campbell/��Ҵ�ý�ƽ��

JILA Fellow and University of Colorado Boulder physics professor Cindy Regal remarked, "The NQN will be a unique facility for quantum discoveries and technology. I look forward to seeing the NQN as a national resource in quantum and interfacing with a wide range of JILA research.”

Read the full article about the NQN at this link published by ��Ҵ�ý�ƽ�� Today.

On June 20, 2024, the U.S. National Science Foundation awarded JILA and the University of Colorado Boulder a $20 million grant to create the National Quantum Nanofab (NQN), a cutting-edge facility poised to revolutionize quantum technology.

JILA Fellow and University of Colorado Boulder physics professor Cindy Regal remarked, "The NQN will be a unique facility for quantum discoveries and technology. I look forward to seeing the NQN as a national resource in quantum and interfacing with a wide range of JILA research.”

Off

Traditional

White

A Drum Sounding Both Hot and Cold

Steven Burrows — Wed, 08 Nov 2023 18:04:49 +0000

A Drum Sounding Both Hot and Cold Steven Burrows Wed, 11/08/2023 - 11:04

Kenna Hughes-Castleberry / JILA Science Communicator

A SiN resonator under localized heating. Different modes have different effective temperatures depending on the spatial overlap between the local temperature and the dissipation density of the mode. Image credit: Steven Burrows / JILA

When measuring minor changes for quantities like forces, magnetic fields, masses of small particles, or even gravitational waves, physicists use micro-mechanical resonators, which act like tuning forks, resonating at specific frequencies. Traditionally, it was assumed that the temperature across these devices is uniform.

However, new research from JILA Fellow and University of Colorado Boulder physics professor Cindy Regal and her team, Dr. Ravid Shaniv and graduate student Chris Reetz has found that in specific scenarios, such as advanced studies looking at the interactions between light and mechanical objects, the temperature might differ in various resonator parts, which leads to unexpected behaviors. Their observations, published in Physical Review Research, can potentially revolutionize the design of micro-mechanical resonators for quantum technology and precision sensing.

“In quantum science experiments, understanding this temperature difference’s ramifications will allow you to generate your mechanical quantum state with better fidelity and keep it unperturbed for longer, both essential starting points for quantum applications,” elaborated JILA postdoctoral research associate and first author Ravid Shaniv.

The Modes of Minute Measurers

Due to their flexible design, micro-mechanical resonators are a standard tool in many different fields of physics. These devices are often made of silicon or similar materials and can take various shapes: beams, cantilevers, membranes, or disks. Their small size allows them to oscillate at high frequencies, often in the megahertz (MHz) range to gigahertz (GHz).
The versatility of a micro-mechanical resonator’s design also allows physicists to fine-tune their oscillations. Just as a guitar string can vibrate in multiple ways (with the whole string moving back and forth or just parts wiggling while the rest remains still), micro-mechanical resonators can oscillate in different patterns or “modes.” The most familiar mode is the fundamental mode, where the entire structure moves in unison. But there are also higher-order modes, where other resonator parts move in more complex patterns.

To measure a resonator’s motion, physicists use laser beams. The resonator acts like a “moving mirror,” and the laser light that bounces off carries information about its position. When compared to light that bounces off a separate fixed mirror, an interference pattern is developed, revealing the resonator's motion to ultra-high precision.

Over the years of observing these modes optically and discussing them with other physicists, Shaniv and Regal realized something interesting. “People have observed that some of these modes exhibit more thermal motion than others,” Shaniv stated. “Typically, people want to eliminate this motion as much as possible because it could overshadow any small effect they want to sense.”

Physicists have posited that this excess of thermal motion could be due to the resonator absorbing laser light in the form of heat. Different resonator modes can have different movement patterns, leading to varying areas of stress or strain, which can, in turn, lead to distinct magnitudes of thermal motion.

In many observations, the more complex the mode of the resonator, the more it's thermal energy deviates from previous theories, which suggested the temperature for every mode was identical. Shaniv continued: “We wanted to track down the reason for that and how you can achieve the optimum design for these modes.”

Creating Temperature Profiles

To dive deeper into this temperature conundrum, Shaniv and Regal created specific temperature profiles for each mode. To do this, the researchers utilized a “phononic crystal” comprised of silicon nitride. The crystal acted as a playground where the researchers could engineer the resonator modes and generate varying temperature profiles, allowing them to observe the induced thermal motion of each resonator mode.

To create the temperature profile, the team heated a point on the crystal to very high temperatures while keeping the resonator edge at room temperature. After a profile was developed and thermal motion was measured, the researchers found some rather interesting results. Depending on the mode geometry, some modes showed increased thermal motion, while, even though parts of the resonator were extremely hot, others showed only mild heating, and some exhibited no heating at all. “By turning the knob all the way in the experiment, you could see this striking difference,” elaborated Regal.

Shaniv continued: “Looking at these really large temperature differences between modes, we were able to construct the temperature profile of a resonator directly from measured thermal motion and even find some material parameters that are typically not straightforward to evaluate, for example, the emissivity, which is how much radiation our device emits.”
By seeing which modes correlated to different thermal motions, the team could begin to predict how the resonators’ performance may change depending on their mode. As Regal explained: “A natural next step is to ask whether these concepts can be put to use not only in understanding how to keep resonators cold for quantum studies but also in thermal sensing.”

Designing Better Resonators

With the insights gained, the scientific and engineering communities could make significant strides in designing and applying these minuscule yet crucial devices. “We actually gave in our paper a real figure of merit, with which groups can work in this direction,” Shaniv elaborated. “For example, we now have a specific parameter to throw as a constraint into the computer and try to generate the best possible resonator.”

New research from JILA Fellow and University of Colorado Boulder physics professor Cindy Regal and her team, Dr. Ravid Shaniv and graduate student Chris Reetz has found that in specific scenarios, such as advanced studies looking at the interactions between light and mechanical objects, where the temperature might differ in various resonator parts, which lead to unexpected behaviors. Their observations, published in Physical Review Research, can potentially revolutionize the design of micro-mechanical resonators for quantum technology and precision sensing.

Off

Traditional

White

Membranes suspending a mass

Steven Burrows — Fri, 31 Mar 2023 19:44:54 +0000

Membranes suspending a mass Steven Burrows Fri, 03/31/2023 - 13:44

In our work published in Physical Review Applied, we study how mode quality factor depends on suspending a mass on a type of membrane resonator known as a trampoline. Surprisingly, the quality factor becomes independent of the mass in the large-load regime, for any tensioned resonator, which explains previous related results and will enable new design perspectives.

Mechanical resonators featuring large tensile stress have enabled a range of experiments in quantum optomechanics and precision sensing. Many sensing applications require functionalizing tensioned resonators by appending additional mass to them. However, this may dramatically change the resonator mode quality factor, and hence its sensitivity.

In our work published in Physical Review Applied, we study how mode quality factor depends on suspending a mass on a type of membrane resonator known as a trampoline. Surprisingly, the quality factor becomes independent of the mass in the large-load regime, for any tensioned resonator, which explains previous related results and will enable new design perspectives.

Off

Traditional

White