quantum optical behaviors matter waves

Scientists Harness Matter Waves to Reveal New Quantum Optical Behaviors

Introduction: A Novel Discovery in Quantum Optics

Dr. Dominik Schneble, a Professor in the Department of Physics and Astronomy, and his team have unveiled a novel set of system conditions, illuminating cooperative radiative phenomena and addressing a quantum optics question dating back 70 years.

Discovery of Collective Spontaneous Emission Effects

The team's discovery of novel collective spontaneous emission effects in an array of artificial atoms is featured in Nature Physics, alongside a theoretical study published in Physical Review Research.

What is Spontaneous Emission?

The phenomenon of spontaneous emission occurs when an excited atom descends to a lower energy level, emitting a single photon of electromagnetic radiation. This decay process is characterized by an exponentially decreasing probability of the atom staying in its excited state as time elapses.

Historical Background: Dicke's Contribution to Quantum Optics

In 1954, Princeton physicist R. H. Dicke investigated the effect of placing an unexcited atom near an excited one. He demonstrated that the probability of observing the excited atom drops to one-half. This behavior arises from the excited system encompassing two scenarios:

• In-phase atomic alignment enhances emission (Superradiance)
• While out-of-phase alignment suppresses it (Subradiance)

When both atoms begin in an excited state, the resulting decay is invariably superradiant.

Schneble's Novel Approach Using Ultracold Atoms

The research by Schneble and collaborators involved the use of ultracold atoms arranged in a one-dimensional optical lattice to construct synthetic quantum emitters. These emitters decay through the emission of slow atomic matter waves, as opposed to the high-velocity photon emission characteristic of conventional systems.

This system enabled access to novel collective radiative regimes, allowing the team to investigate weakly and strongly interacting many-body excitation phases.

Advancements in Manipulating Emitter Arrays

Through the preparation and control of emitter arrays exhibiting weakly and strongly interacting many-body excitation phases, the researchers showcased directional collective emission and examined the relationship between retardation effects and superradiant and subradiant dynamics.

Implications for Quantum Information Science and Technology (QIST)

"Dicke's concepts hold profound relevance in quantum information science and technology (QIST)," notes Schneble, a member of Stony Brook's Center for Distributed Quantum Processing (CDQP). "Significant efforts are underway to leverage super-and subradiance in quantum emitter arrays coupled to one-dimensional waveguides."

Unparalleled Control of Subradiant States

"In our research, we achieve unparalleled control in preparing and manipulating subradiant states," says Schneble. "We can suppress spontaneous emission and identify where radiation is localized within the arrya—a demonstration that, to our knowledge, is the first of its kind."

Team Contributions and Novel Insights

The research conducted by the stony Brook team, which included former Ph.D. students Youngshin Kim and Alfonxo Lanuza, offers novel insights into fundamental principles of quantum optics.

Challenging Assumptions in Dicke's Theory

Schneble clarifies that, in Dicke's theory, photons are not actively involved since they travel quickly between adjacent emitters on the decay timescale. However, this assumption can be disrupted in scenarios such as in long-distance quantum networks, where a guided photon emitted from a decaying emitter may take significantly longer to reach its neighbor.

Exploring Slow Matter Waves: A Unique Quantum Regime

The researchers were able to explore this uncharted regime, as the emitted matter waves in their system are billions of times slower than  photons.

Insights from Co-author Youngshin Kim

Co-author Kim explains, "We observe that collective decay from a superradiant state with a single excitation takes time to develop. This process occurs only once adjacent emitters have had the opportunity to communicate."

The Challenge of Tracking Slow Radiation in Systems of Emitters

The researchers highlight the theoretical difficulty of tracking slow radiation in a system of emitters.

According to co-author Lanuza, the challenge is like a complex game of catch and release: "A photon emitted by an atom can be caught and released several times before escaping, or it may remain bound to the atom. The rules become more complicated when multiple atoms and photons are involved—photons exchanged between atoms, bouncing off excited atoms, and being trapped between atoms are just a few of the many processes occurring."

Mathematical Solutions for Collective Atomic Decay Behaviors

Despite the intricate interactions between photons and atoms, he successfully derived mathematical solutions for a system involving two emitters with up to two excitations and arbitrary vacuum coupling. This aspect of the research could pave the way for uncovering additional complex or unexpected collective atomic decay behaviors in future studies.

Conclusion: The Future of Many-Body Quantum Optics

Schneble concludes that their results on collective radiative dynamics underscore the utility of ultracold matter waves as a versatile approach for examining many-body quantum optics in spatially extended, ordered systems.

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