Banner image: Physicist Jun Ye gives U.S. Rep. Joe Neguse a tour of his lab at JILA on the CU Boulder campus. (Credit: Glenn Asakawa/CU Boulder)
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UPDATED: Jan. 26, 2024
In the 17th century, a Dutch merchant named Antony van Leeuwenhoek began experimenting with making new microscope lenses and, in the process, plunged humanity into a new world鈥攖his one teeming with previously-undiscovered life, from small bacteria to single-celled algae and more.
More than 400 years later, scientists are in the midst of an equally-important revolution. They鈥檙e diving into a previously-hidden realm鈥攆ar wilder than anything van Leeuwenhoek, known as the 鈥渇ather of microbiology,鈥� could have imagined. Some researchers, like physicists Margaret Murnane and Henry Kapteyn, are exploring this world of even tinier things with microscopes that are many times more precise than the Dutch scientist鈥檚. Others, like Jun Ye, are using lasers to cool clouds of atoms to just a millionth of a degree above absolute zero with the goal of collecting better measurements of natural phenomena.听
鈥淭o borrow a phrase, we鈥檙e going where no one has gone before,鈥� said quantum physicist Ye, a fellow at between CU Boulder and the U.S. (NIST).听
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A quantum dictionary
Noah Finkelstein is a professor of physics at CU Boulder and a member of the Physics Education Research group. Here, he explains some of the most important, and strangest, concepts in quantum physics.
Check out听听to learn more about quantum physics.
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Murnane, Kapteyn and Ye听are among a growing number of Colorado researchers dedicating their careers to the exploration of quantum physics, the study of the universe at its smallest scales. In this microscopic world, electrons can exist in several places at the same time. Particles tunnel through solid matter and hop out the other side, while atoms tick like tiny pendulums quadrillions of times per second.
Just as microscopes paved the way for antibiotics and modern medicine, precise control of the quantum world is revolutionizing听everything from timekeeping and medical imaging to space travel and听next-generation electronic听and energy devices. And both its birth and growth are rooted in Colorado.听
In the Centennial State, this revolution emerged from the work of countless scientists, including four Nobel Prize laureates (see 鈥溾��) working over decades. Today, CU researchers and their collaborators continue to lay the groundwork, with research centers like and Quantum Systems through Entangled Science and Engineering (Q-SEnSE). These efforts are helping to transform the state into a new Silicon Valley, only this time, a Quantum State.
鈥滱s I walk down the halls of JILA, I often reflect on the amazing work that has taken place here,鈥� said Scott Sternberg, executive director of the CUbit Quantum Initiative, which seeks听to reinforce Colorado's pominence in quantum science and technology.听鈥淢y mind, however, quickly turns to the great work currently taking place and it鈥檚 enormous impact on our future.鈥�
Quantum, quantum everywhere
Sternberg, who previously worked in economic development in and around Boulder, sees the growth in quantum discovery as a natural outcome of the Boulder ecosystem.听
鈥淒ecades of investments in the form of both human and financial capital have catapulted Boulder into international recognition,鈥� he said. 鈥淐ombining the resources of the university with the connections to the federal laboratories, and fueled by the entrepreneurial spirit exhibited here, is a winning equation.鈥�
The field of quantum science was pioneered by researchers like Niels Bohr, whose ideas about the structure of atoms still pop up in every high school chemistry textbook; Maria Goeppert Mayer, who predicted how atoms absorb intense laser light; and Werner Heisenberg, whose uncertainty principle states, for example, that you can accurately measure the location of a particle or its velocity but not both at the same time. Scientists and engineers, in turn, built off those insights to design devices like transistors, semiconductors and lasers鈥攚hich take advantage of the quantum mechanical nature of electrons and light waves to run all modern electronics and the internet.
But those advances are also just the beginning.
Imagine a future in which you commute to work using a navigation app that keeps running, even when you duck into a subway station out of range of GPS; where microscopes can record real-time videos from deep inside living cells or nanodevices; and where new supercomputers can discover and test novel drugs in record time.
This new burst of quantum research embraces the strangest properties of physics. They include entanglement, a kind of 鈥渟pooky鈥� connection between particles or atoms; and superposition, or objects existing in multiple states at the same time (see 鈥溾��). Scientists are also striving to manipulate quantum systems to enable new microscopes or to bring quantum effects to the realm of larger things鈥攅nabling properties they didn鈥檛 know were possible.
These concepts aren鈥檛 always easy to grasp, said theoretical physicist Ana Maria Rey. Ultimately, they鈥檙e not like any of the 鈥渃lassical鈥� physics humans encounter during our day-to-day lives.听
鈥淭he quantum realm is extremely rich and complex, and fully understanding it can be as complicated as navigating the sea without a compass,鈥� said Rey, a NIST and JILA fellow.听
Many companies, however, are beginning to explore those waters, including several businesses founded by CU Boulder researchers. They include (formerly ColdQuanta), , , ,听, ,听, 听and . In 2023, the U.S. Department of Commerce named听, a consortium of companies, universities and more, as听one of .听
Quantum for sensing our world
That new quantum revolution began, in many ways, with a clock鈥攏ot a wristwatch or a grandfather clock, but a device that can do a lot more with the help of atoms.
Today, scientists at JILA and NIST are developing some of the world鈥檚 most precise and accurate atomic clocks. They build off decades of work by Nobel laureates Jan Hall, Dave Wineland and Eric Cornell and Carl Wieman.
First, researchers collect clouds of atoms and chill them down, then trap those atoms in an 鈥渁rtificial crystal鈥� made of laser light. Next, they hit the atoms with yet another laser. Like pushing a pendulum, that laser beam starts the atoms 鈥渢icking,鈥� causing them to oscillate between energy levels at a rate of quadrillions of times per second.
Researchers at CU Boulder and LongPath Technologies are using quantum sensors to detect methane leaks from oil and gas sites. (Credit: CU Boulder)
These clocks are also incredibly sensitive. Ye, for example, demonstrated an atomic clock that can if you lift it up by just a millimeter. Ye, who鈥檚 also the director of CUbit, leads a center on campus funded by the National Science Foundation called Quantum Systems through Entangled Science and Engineering (Q-SEnSE).
He imagines using such devices to, for example, predict when a volcano is about to erupt by sensing the flow of magma miles below Earth鈥檚 surface.听
鈥淔or me, one of the most promising technological avenues is quantum sensors,鈥� said Rey who has worked with Ye over the years to take atomic clocks to greater and greater levels of precision. 鈥淲e鈥檝e already seen that quantum can help us do better measurements.鈥�
A team of engineers at CU Boulder is using different quantum sensors to detect methane leaking from natural gas operations in the West.
Meanwhile, CU Boulder鈥檚 Svenja Knappe and her colleagues employ a quantum sensor called an optically-pumped magnetometer, or OPM, to dive into the complex territory of the human brain.
鈥淭he first time I went to a neuroscience meeting, the neuroscientists there looked at me like I was from Mars,鈥� said Knappe, associate professor in the .听
Knappe鈥檚 OPMs each measure about the size of two sugar cubes. They contain a group of atoms that change their orientation of their "spins," a strange property of atoms and particles, in response to the magnetic fields around them. It鈥檚 a bit like how the needle in a compass always points north. She and her colleagues are employing the sensors to measure the tiny blips of energy that neurons emit when humans move, think or even just breathe.听
Neuroscientists are already using to collect maps of the brain鈥檚 activity, or magnetoencephalograms (MEGs). They are important tools for studying or diagnosing illnesses like schizophrenia and Parkinson鈥檚 Disease. To date, Knappe and her colleagues have sold sensors to about a dozen clients through a Boulder-based company called .
听鈥淭his is not a technology that's 20 years out. Quantum sensors can make an impact on your life now,鈥� she said.
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Artist's depiction of an Earth-sized planet orbiting a star roughly 100 light-years from our own. (Credit:听NASA/Goddard Space Flight Center)
Quantum for probing the mysteries of the universe
By going smaller and ever more precise, scientists might also pursue questions that have eluded them for decades.
For instance: What is dark matter?
This mysterious substance constitutes about 84% of the mass in the universe, but scientists have yet to identify what type of particle it鈥檚 made of. Dark matter is, as far as physicists can tell, completely invisible and rarely interacts with normal matter. But Ye suspects that some candidates for dark matter in his atomic clock鈥攏ot very often, but often enough that he and his colleagues could, theoretically, detect the disturbance.
Jun Ye shares his team's new atomic clock, the world's most precise yet. (Credit: NIST)
鈥淪ay you have a clock here in the U.S. and another clock somewhere near the North Pole,鈥� Ye said. 鈥淚f one clock was speeding up, while the other was slowing down, and if you have accounted for all other known effects, that might indicate that we鈥檙e seeing different fields pass Earth as it moves through the universe.鈥�
Other are narrowing the search for dark matter using a .
Quantum researcher Scott Diddams听is turning quantum sensors toward space to far away from Earth.听
Diddams is听as a professor in the Department of Electrical, Computer and Energy Engineering听and director of the Quantum Engineering Initiative. He explained that when 鈥渆xoplanets鈥� orbit their home stars, they tug on those stars a little bit, causing them to wobble.
Telescopes on the ground can spot those wobbles, but the changes are very, very faint.听
鈥淎s a star is being pulled away from us, the colors of light look ever so slightly more red. As it鈥檚 being pulled toward us, its light will look slightly more blue,鈥� he said. 鈥淎nd by slight, I mean less than one part in 1 billion.鈥�
He uses a powerful type of laser called a frequency comb to help narrow in on that slight shift. More than 20 years ago, the physicist was part of the team that invented these lasers when he was a postdoctoral scientist at JILA鈥攁t first, researchers used them to count out the ticking in atomic clocks. But if you also install one of these tools in a telescope on the ground, Diddams said, it can act almost like a ruler for light waves. Astronomers can deploy these rulers to more precisely measure the color of light coming from distant stars, potentially finding planets hiding just out of view.
Diddams鈥� colleagues are already doing just that every night from two observatories on the ground. Teams led by Penn State have installed frequency combs at the and the . In 2023, Diddams launched an effort to explore how frequency combs might help create an infrared telescope that would span the globe, syncing up observations from instruments across the planet and in space.听
鈥淚t鈥檚 a really interesting example of transitioning technology first developed at JILA out of the lab and into real experiments,鈥� he said.听
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Interactive timeline
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Artist's depiction of a laser heating up bars of silicon many times thinner than the width of a human hair. (Credit: Steven Burrows/JILA)
Quantum for taking better images
When Antony van Leeuwenhoek first observed the green cells belonging to algae from lakes in the Netherlands, he was seeing the world at about 200 times its normal size.
Physicists Margaret Murnane and Henry Kapteyn have spent their careers trying to look deeper than that鈥攔oughly 100 to 1,000 times deeper.听
A little more than a decade ago, the duo built the world鈥檚 first X-ray laser that could fit on a tabletop. And they did it by tapping into the quantum nature of electrons and atoms.听
Margaret Murnane and Henry Kapteyn in their lab on campus. (Credit: Glenn Asakawa/CU Boulder)
The team uses a laser to pluck electrons in atoms, essentially making them vibrate violently鈥攁kin to what happens if you pluck a guitar string really hard. In the process, the atoms, like guitar strings, can snap, breaking apart but also emitting excess energy in the form of X-ray light. The resulting beams, which are today among the fastest听microscopes on Earth, oscillate more than a quintillion, or a billion billion, times per second.听
Murnane and Kapteyn鈥檚 group at CU Boulder has used these lasers to better understand how heat flows in nanodevices thinner than the width of a human hair. They鈥檝e also found that light can manipulate the magnetic properties of materials more than 500 times faster than scientists previously predicted.
NIST and Imec, a company that develops semiconductors and other devices, are already employing Murnane and Kapteyn鈥檚 lasers to design new nano-sized electronics.听
听听 听
鈥淪eeing is understanding,鈥� said Murnane, a JILA fellow and distinguished professor of physics at CU Boulder. 鈥淲e still can鈥檛 see everything we need to see to be able to understand nature.鈥�
To build 鈥渢he microscopes of tomorrow,鈥� Murnane and Kapteyn helped launch a with funding from the U.S. National Science Foundation. In the 1990s, they started a company called to sell their X-ray lasers.
They鈥檙e also continuing to push the limits of what atoms are capable of. Kapteyn said that the team would like to one day create an X-ray laser so powerful that it could see inside human tissue. Such a machine would allow doctors to zoom in on specific regions of the body, and with much greater resolution than current X-rays.听
鈥淭here are a lot of quantum questions that are still outstanding in this area around how far we can push this technology,鈥� said Kapteyn, JILA fellow and professor of physics.
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Artist's depiction of a qubit formed from an ytterbium atom trapped in laser light. (Credit: Steven Burrows/JILA)
Quantum for making faster computers
There may be no quantum technology that gets as much hype as quantum computers.
Some of the largest technology companies in the world, including听Google, Amazon, Microsoft and IBM, are trying their hand at developing computers that are based on unusual properties of quantum physics. Experts believe quantum computers could one day solve problems that even the largest supercomputers on Earth right now couldn鈥檛.听
But researchers at CU Boulder say quantum computers that can solve听problems relevant to the lives of real people may still be a long way away. For one thing the quantum processors currently available often produce too many errors to do a lot of basic calculations.
鈥淨uantum computers may be really good for the specific tasks they are designed for,鈥� said Shuo Sun, a JILA fellow and assistant professor of physics at CU Boulder. 鈥淏ut they won鈥檛 be good at everything."听
Cindy Regal, center, helped to consult on a mural by artist Amanda Phingbodhipakkiya in Denver's Washington Park celebrating women in physics. (Credit:听Amanda Phingboddhipakkiya)
Researchers at CU Boulder, however, are striving to design new and better qubits. Like the bits that run your home laptop, qubits form the basis for quantum computers. But they鈥檙e a lot more flexible: Qubits can take on values of zero or one, like normal bits, but they can also exist in a ghostlike state, or 鈥渟uperposition,鈥� of zero and one at the same time.听
Cindy Regal, a fellow at JILA and associate professor of physics at CU Boulder, and her colleagues are using a technique called optical tweezing to make qubits out of neutral atoms, or atoms without a charge. Optical tweezers deploy laser beams to carefully move around and arrange those atoms. Scientists can then build complex lattices made up of atoms, carefully controlling how they interact with each other.
Sun, in contrast, is designing a different kind of qubit by implanting lone atoms inside diamonds and other crystals.
Regal noted that even if these qubits don鈥檛 wind up in a computer anytime soon, they can still help scientists answer new questions鈥攁llowing them to simulate, for example, the physics of weird states of matter in a controlled lab setting.
Some experts have even imagined quantum computers leading the hunt for new medicines. These devices might, decades from now, scan through large databases of molecules, looking for ones with the exact chemical behavior doctors want.听
In the end, Murnane said if quantum researchers want to bring their quantum technologies out of the lab, they need to continue to build connections with researchers beyond physics鈥攃ollaborating with engineers, materials scientists, astrophysicists, biologists and more.
鈥淚f you want your research to have a big impact, you need to look beyond your field,鈥� Murnane said.
Ye noted that the most amazing quantum technologies may be the ones that scientists haven鈥檛 dreamed up yet. Like van Leeuwenhoek discovered four centuries ago, the deeper you look into the world, the more surprises you鈥檒l find.听
鈥淚t鈥檚 just like when people first invented a microscope,鈥� Ye said. 鈥淭here鈥檚 an entire world down there filled with bacteria, and we never realized that.鈥�
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