Insider Brief
- Stevens researchers and collaborators have proposed a laser-pulse technique designed to control quantum systems while reducing unwanted multiphoton processes caused by intense laser fields.
- The theoretical method uses a sequence of 12 short, low-intensity laser pulses, with their timing, intensity, frequency and phase calculated to reproduce the effect of a longer, stronger pulse.
- Published in the Journal of the Optical Society of America B on September 10, 2026, the study could have applications in quantum computing, quantum sensing, spectroscopy, molecular physics, biology and medicine.
PRESS RELEASE — Quantum technologies are poised to transform fields ranging from medicine and sensing to computing and communications by manipulating the energy states of atoms and molecules. These manipulations are achieved by controlling quantum states with laser pulses. However, the intense laser fields often required for this control can cause unwanted effects disrupting the very system they aim to manipulate. Now, Stevens researchers and their collaborators have developed a novel method that enables precise control of quantum systems without these undesirable effects.
“A laser is a device that creates a very narrow, highly directional beam of light,” explains Svetlana Malinovskaya, professor at Charles V. Schaefer, Jr. School of Engineering and Science, whose research focuses on quantum science and controlling quantum systems. “Unlike sunlight or light from regular bulbs or flashlights that scatters in all directions, a laser produces light in which all waves move together in a highly synchronized way allowing the light to be very focused and controlled with remarkable precision.”
When this powerful wave reaches a quantum system, its units of energy called photons are absorbed by the atoms and molecules of that system, pushing these particles into a higher-energy state. If the laser field is very intense, an atom or molecule may interact with multiple photons at once, opening additional pathways between its energy states and disrupting the desired dynamics in the quantum system making it difficult to predict or control. These unwanted interactions are called multiphoton processes.
“By shining laser light on molecules, we can excite molecular vibrations in a controlled way and learn about molecular properties,” says Malinovskaya. “But when very strong laser fields are used for precise quantum control, they can also trigger unwanted multiphoton processes allowing the molecule to access many different states and pathways, making its behavior much more difficult to predict and control.”
That unpredictability is a major problem when scientists need precise control—for example, when manipulating quantum systems for quantum computing or making highly sensitive measurements. “That’s not what we need, particularly for the precision measurements required in quantum computing or quantum sensing,” Malinovskaya says. “In those systems, every photon counts.” In these applications, light-matter interactions must be controlled with extreme precision, so researchers want to use just enough light to control a quantum system without introducing unwanted processes.
In their new study, Malinovskaya and her collaborators propose to solve this problem with what they call a “digitized” version of a laser pulse. Their calculations show that using a series of 12 short, low-intensity laser pulses would produce the same effect as one long, intense pulse, but without pushing the atoms or molecules into unwanted states that are difficult to control.
“Instead of using one very strong laser pulse, we suggest mimicking its effects with a carefully programmed sequence—or train—of weak pulses,” Malinovskaya explains. “Each pulse carries much less energy, but its timing, intensity, frequency and phase are precisely calculated and controlled.” The researchers calculate that this train of pulses can produce the same gradual transfer of a quantum system from one state to another as the much stronger pulse—achieving the same desired outcome while keeping the laser intensity much lower at each step.
Titled, Digitizing ultrafast adiabatic passage with a pulse train, the paper was published in the Journal of the Optical Society of America B on September 10, 2026.
This new technique could benefit quantum sensors, quantum computers and quantum simulators, where reliable preparation and manipulation of quantum states are essential for making accurate measurements or performing calculations. It may also be particularly helpful in molecular physics or spectroscopy, where intense laser pulses can produce unwanted effects that interfere with measurements. In biology and medicine, where laser-based technologies are widely used for imaging to diagnose diseases, reducing the intensity of laser pulses can minimize damage to sensitive cells and tissues, so the new method offers a way to solve this problem.
Malinovskaya notes that while the paper is theoretical, it lays out all the necessary calculations. “The next step will be to actually test it,” she says. “When demonstrated experimentally, this approach will open a new way to precisely control quantum systems with weaker laser fields, making it easier to use in practical applications.”
