Igor Pikovski Reflects on the Quantum Mechanics Centennial and Stevens’ More Than Half a Century Contribution to the Field, as Well as the Future

In 1925, German physicist Werner Heisenberg arrived at a small island in the North Sea called Helgoland. He was running away from big cities in hopes to ease his hay fever. As he spent the next 10 days in pristine nature, he developed the foundations of quantum mechanics — a theory that explains the behavior of matter and energy at the atomic levels.

Well, at least that’s how the legend goes.

In reality, things were a little different, says Igor Pikovski, Stevens Geoffrey S. Inman Junior Professor of Physics, whose research focuses on quantum physics. Pikovski recently returned from a conference devoted to the 100th anniversary of quantum mechanics, which fittingly took place on the Helgoland island. Quantum mechanics was developed by multiple people over the course of time, he says. Although Albert Einstein is largely credited for the theory of relativity, that was not the case for quantum mechanics where multiple contributors helped develop the field.

According to historians, when Heisenberg first returned to the mainland, he wrote to his supervisor, Niels Bohr, that his sojourn was a waste of time — he didn’t think of it as productive. “Later, however, as he discussed his ideas with others, his colleagues realized, oh, we can build on that,” says Pikovski, who is also a Lektor at Stockholm University. “But hey, why not celebrate a quantum mechanics centennial with a conference on Helgoland?”

The conference — devoted to the increasingly fruitful intersection between the foundations of quantum mechanics and its real-world applications — was very multidisciplinary in nature, with topics spanning from black holes to quantum computing and everything in between. Luminary figures in the field, including four Nobel Prize winners, discussed how quantum mechanics evolved from a pie in the sky to a prominent reality.

Anton Zeilinger and Alain Aspect, Nobel Prize winners who pioneered quantum entanglement, a phenomenon in which two or more particles are linked in a way that they share the same state, even when separated by long distances — talked about using this phenomenon in modern quantum information science. David Wineland and Serge Haroche, who also shared a Nobel Prize, talked about measuring and manipulation of quantum systems at the levels of individual atoms.

Also in attendance was Bill Unruh, who studies black hole and space time quantum physics at the University of British Columbia and Juan Maldacena from Princeton University, who focuses on quantum gravity. There was Mikhail Lukin from Harvard University, whose research focuses on trapping and manipulating atoms for future quantum computing. Meanwhile, another attendee was John Preskill from California Institute of Technology who studies quantum error correction used in quantum computing as well as quantum phenomenon in black holes.

“These are completely different facets of quantum physics,” Pikovski says. “It’s really impressive to see the multitude of quantum topics and how they are all interconnected.”

One of the main themes of the conference was the foundations of quantum theory, and the big open questions that remain. Repeatedly, one topic was singled out: how can we find out if gravity is also a quantum theory. That’s exactly what Pikovski studies in his lab. His research focuses on testing quantum gravity, and more recently on detection of gravitons — particles believed to mediate the force of gravity similar to how photons mediate electromagnetism. Unlike photons, however, gravitons were thought to be undetectable — until Pikovski’s recent paper proposed a clever experiment to spot them.

“At the conference, I explained how we can detect gravitons today, which was believed to be impossible until our paper came out last year,” Pikovski says. Published in the journal Nature Communications, Detecting single gravitons with quantum sensing became the most downloaded paper in physics in 2024. Pikovski’s more recent papers include Testing quantum theory on curved space-time with quantum networks published in Physical Review Research, and Probing curved spacetime with a distributed atomic processor clock in PRX Quantum.

This work is important to experimentally test how to reconcile differences between the general theory of relativity, also known as Einstein's theory of gravity, and quantum mechanics. Physicists haven’t been able to do it for a century — because of several challenges.

One is that Einstein’s general relativity theory, and quantum mechanics, both our best descriptions of the universe, are likely incompatible at some scale. Traditionally this was studied at extremely high energies and small scales, like those found within black holes or at the origin of the universe. Attempts to unify them – a theory of everything – so far has been inconclusive.

Another problem is that the general theory of relativity views spacetime as a continuous entity, while quantum mechanics describes the universe in terms of discrete quanta; attempts to "quantize" gravity — or apply the principles of quantum mechanics to gravity — break the math.

Finally, testing it experimentally has been challenging too — until now. “That’s where my research comes in, showing that we can actually provide experiments that had been considered impossible,” Pikovski says. “And we show that thinking about quantum foundations, while using quantum technologies, opens an entirely new capability to use experiments to answer these questions.”

These breakthroughs in quantum technologies put quantum mechanics itself already on the brink of a revolution — partly because the new technologies allowed manipulating atoms better, and partly because companies realized that quantum phenomena can have real-life applications, such as unbreakable encryption of information in computers and networks. “In the past 10 years, quantum has made it out of the labs and into reality,” Pikovski says. “Now there’s a race to build a quantum computer and quantum networks.” These developments might be key to tackling the big open questions of quantum physics itself.

Stevens has been a strong contributor to quantum science for decades. The university’s first mention of quantum mechanics dates back to a March 10, 1926 lecture on the structure of an atom — less than a year after Heisenberg’s Helgoland trip. As early as 1960, Stevens researchers attempted to quantize the general theory of relativity. “Our Department of Physics has been very focused on quantum research for decades, long before it became fashionable,” Pikovski shares. “Stevens was also one of the main hubs worldwide for gravity research in the 60s, with many future leaders in gravity coming here for discussions.” And it had luminary figures of its own moving the field forward, including James Anderson who led quantum research at Stevens for 40 years and David Ritz Finkelstein who wrote a book about merging Einsteins and Heisenberg ideas.

Today, Stevens occupies a little niche of extremely good research in quantum science and gravity that led to creating quantum devices and quantum engineering. “That’s different from other places where this research is more recent,” Pikovski notes.

This breadth of cumulative quantum knowledge recently earned Stevens a government recognition. It also evolved into a Center for Quantum Science and Engineering, which is now bearing fruit.

Stefan Strauf’s lab is manipulating single photons, which is key to creating secure quantum networks. Yuping Huang’s lab has developed quantum computing and sensing technologies in a successful startup QPhoton, which was acquired by Quantum Computing Inc. And Ting Yu’s research group studies how quantum systems interact with their environments, sometimes losing their quantum properties in a phenomenon known as quantum decoherence, which is important to better understand the quantum-classical transition and for practical applications. “Stevens is a rare place where quantum theoretical research on the foundations of quantum theory and practical applications come together,” Pikovski says.

Today, Pikovski is busy planning yet another Stevens quantum center, which will focus on fundamental research that can tackle quantum science and gravity simultaneously. “We have many open questions about quantum theory that remain a mystery and many surprises to be uncovered, especially related to gravity,” he says. “For the first century of quantum mechanics, it was mostly a dream to control individual quanta and see quantum phenomena on large scales. In the second century it’s poised to revolutionize so many real, tangible things and serve humanity. It’s exciting to be part of this effort, particularly at the institution that recognized the discipline’s importance early on.”