Graeme Smith

JILA Undergraduate Research Assistant Luke Coffman Awarded Prestigious Goldwater Scholarship

Steven Burrows — Mon, 22 Apr 2024 17:31:55 +0000

JILA Undergraduate Research Assistant Luke Coffman Awarded Prestigious Goldwater Scholarship Steven Burrows Mon, 04/22/2024 - 11:31

Kenna Hughes-Castleberry / JILA Science Communicator

JILA Undergraduate Research Assistant Luke Coffman

Luke Coffman, a dedicated undergraduate research assistant at JILA, part of the University of Colorado Boulder, has been awarded the prestigious Goldwater Scholarship for the 2024 academic year. This award places Coffman among a select group of 438 students nationwide, who are recognized for their significant achievements and potential in research in science, technology, engineering, and mathematics.

As a junior from St. Charles, Missouri, Coffman is pursuing an ambitious academic path with majors in physics and mathematics, supplemented by a minor in quantum engineering. His research at JILA, a leading institute known for its advanced studies in quantum information and related fields, centers on quantum information theory. Specifically, Coffman's work explores the intricacies of entanglement, a quantum phenomenon essential for the next generation of quantum computing and secure communication systems.

Coffman's current project at Oak Ridge National Laboratories involves pioneering methods to distill entanglement. His work, colloquially described as making "quantum lemonade from quantum lemons," focuses on enhancing weak quantum entanglements for practical applications such as teleportation and encryption. This research advances the theoretical framework of quantum mechanics and holds potential for real-world applications in secure communications.

Beyond his research, Coffman actively contributes to the ��Ҵ�ý�ƽ�� community. He serves as co-president of the Society of Physics Students and vice president of the Community of Support for Marginalized Students (COSMOS) within the math department. These leadership roles underscore his commitment to fostering an inclusive academic environment.

Acknowledging the support and guidance from his mentors, Coffman extends his gratitude to notable figures such as Graeme Smith at IQC/JILA, Jacob Beckey and Murray Holland at JILA, and Joshua Combes in ECEE. Their expertise and encouragement have been instrumental in his research and development as a scholar.

CU students Claire Ely and Delaney McNally were also awarded a Goldman Scholarship, recognized for their exceptional contributions to research in their respective fields.

Deborah Viles, director of the Office of Top Scholarships at ��Ҵ�ý�ƽ��, praised the achievement: “All three have made remarkable progress in their research at CU under the guidance of enthusiastic and supportive mentors. We can’t wait to see how their work continues to influence humanity"

Luke Coffman, a dedicated undergraduate research assistant at JILA, part of the University of Colorado Boulder, has been awarded the prestigious Goldwater Scholarship for the 2024 academic year. This award places Coffman among a select group of 438 students nationwide recognized for their significant achievements and potential in science, technology, engineering, and mathematics research.

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Defining the Limits of Quantum Sensing

Steven Burrows — Thu, 12 Jan 2023 19:32:45 +0000

Defining the Limits of Quantum Sensing Steven Burrows Thu, 01/12/2023 - 12:32

Kenna Hughes-Castleberry / JILA Science Communicator

A rendering of broadband sensing using quantum channels. Image credit: Steven Burrows / JILA

There are many methods to determine what the limits are for certain processes. Many of these methods look to reach the upper and lower bounds to identify them for making accurate measurements and calculations. In the growing field of quantum sensing, these limits have yet to be found. That may change, thanks to research done by JILA Fellow Graeme Smith and his research team, with JILA and NIST Fellow James Thompson In a new study published in Physical Review Applied, the JILA and NIST researchers collaborated with scientists at the quantum company Quantinuum (previously Honeywell Quantum Solutions) to try and identify the upper limits of quantum sensing.

Quantum sensors are devices that can be used to measure gravitational waves, magnetic fields, and other physical properties. They can be part of global positioning systems or even satellites. To look at the limits of quantum sensors, the researchers studied how they behave in a type of magnetic field, called an AC magnetic field, that can be created by running an AC current through a coil. To understand various measurements of the magnetic field, the researchers used a quantity called the Quantum Fisher Information (QFI). According to first author and Smith research group graduate student, Anthony Polloreno: “The Quantum Fisher Information is a measure of how much information about a parameter you can extract from a quantum state. In this case, you have a quantum state, like the spin [of a particle], which is interacting with a magnetic field. You're interested in how much information you can extract about the magnetic field.” The researchers defined a new quantity, the integrated QFI (IQFI), a measurement of the upper bound, which they could then use in their mathematical calculations for the limitations of quantum sensing.

By simulating sensing experiments for various durations, the researchers found that the limitations of the quantum sensor were being affected by time. “The idea is that you have a quantum state in an AC magnetic field,” explained Polloreno. “The longer the thing sits in the field, in general, the more information you can learn about the magnetic field, which is why you would expect for instance, the IQFI to maybe increase as a function of time.” Looking at their data, the researchers developed a set of protocols for other scientists to use to test for a quantum sensor's upper bound, using the IQFI value. The researchers believe that these new protocols could be especially important, due to their narrower parameters, for a few applications, including axion detection and dynamical decoupling.

Axion Detection and Dynamic Decoupling

Axions are hypothetical particles that could be the source of dark matter. Other JILA Fellows are in the process of attempting to detect these axions using quantum sensors. “In axion detection, they do these kinds of broad frequency scans, where they're looking for a signal at many frequencies,” Polloreno stated. Having protocols that determine an upper bound for these broad frequency scans can help scientists save time and make more accurate measurements as the protocols start with narrow parameters.

The team's new protocols can also be used to understand dynamical decoupling. According to Polloreno: “Dynamical decoupling is this idea in quantum computation where you have noise that your qubits are experiencing. And you would rather there not be any noise, but of course, there is noise. So, dynamical decoupling tries to reduce some of this noise sensitivity by moving the susceptibility to the noise around to different frequency bands.” The researchers’ new protocols can help to zero in on the right frequency bands for lowering noise susceptibility, thereby assisting scientists with other quantum computing experiments. “From our work we've seen that our new protocols can be applied to both axion detection and dynamical decoupling in completely different ways,” Polloreno elaborated. “One is if you're trying to build sensors to detect things, and the other is if you're trying to isolate your system to not be susceptible to noise.”

Collaboration Leads to Results

This experiment not only illustrated successful collaboration between research teams at JILA, but also illustrated further cooperation with the Colorado-based quantum computing company, Quantinuum (previously Honeywell Quantum Solutions). Quantinuum was brought in via graduate student Joshua Levin, who has recently graduated from the University of Colorado Boulder with his PhD, and who had an internship at Quantinuum at the time of this study. Communicating with colleagues at JILA, Levin and the Quantinuum team were able to help create the theoretical setting of the experiment. “One of the examples we give in the paper is using a transverse field to estimate the amplitude of an AC magnetic field,” said Polloreno. “This example was provided by Josh and the scientists at Quantinuum.” Polloreno and other JILA researchers were grateful to have the benefits of the collaboration with an industrial team. “While at JILA, I've been grateful to work on projects that have been inspired by experimental collaborations,” Polloreno added. “This project was inspired by Graeme's group, James’ group, and Quantinuum. I think JILA’s commitment to connecting theory and experiment helped in this project coming about extremely naturally.”

There are many methods to determine what the limits are for certain processes. Many of these methods look to reach the upper and lower bounds to identify them for making accurate measurements and calculations. In the growing field of quantum sensing, these limits have yet to be found. That may change, thanks to research done by JILA Fellow Graeme Smith and his research team, with JILA and NIST Fellow James Thompson In a new study published in Physical Review Applied, the JILA and NIST researchers collaborated with scientists at the quantum company Quantinuum (previously Honeywell Quantum Solutions) to try and identify the upper limits of quantum sensing.

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Message Received: Studying Quantum Channels

Steven Burrows — Thu, 11 Nov 2021 19:14:32 +0000

Message Received: Studying Quantum Channels Steven Burrows Thu, 11/11/2021 - 12:14

Kenna Hughes-Castleberry / JILA Science Communicator

Model of two quantum channels. Image credit: Steven Burrows / JILA

Physicists study many forms of communication, including quantum communication. Thanks to specific properties of quantum mechanics, like entanglement, information integrity can be better maintained with quantum communications, even being hackproof in some cases. Quantum entanglement is the property that allows two molecules, each in a random quantum state, to be in perfect harmony with each other. This is important, as one common test of quantum communication devices, a.k.a., quantum channels, is to send entangled photons (light particles) down these channels. Entanglement helps when photons are lost or absorbed, as the redundancy in information being sent this way ensures that some of the information will still reach the receiver.

Quantum channels have their own quirks that make them unique to study. In a new paper published in Nature Communications, post-doctoral researcher Vikesh Siddhu of JILA Fellow Graeme Smith's team looked at some of the logistics in using quantum channels to send information. Siddhu analyzed how noise occurring in a quantum channel affects the information it communicates. “Noise in the quantum channel world is essentially coming from interaction with an environment you don't control," Siddhu explained. And since you don't control it, what you're trying to send becomes noisy.”

Using noise as a factor, Siddhu theorized new reasonings for “synergy” between two quantum channels. Synergy refers to an interaction that results in a sum that is greater than the simple sum of its parts. Synergy, Siddhu added, can occur when the two channels work together to send information. “In this case, Channel A can’t send any information on its own, but when used in conjunction with the other channel, Channel B, it becomes useful,” Siddhu clarified. “Channel B, on the other hand, can send information on its own, but when it gets combined with the seemingly useless Channel A, it can send even more information.” Common sense would suggest that the useless channel would negatively affect the transmission of quantum information, but Siddhu found it was quite the opposite.

In his paper, Siddhu described this puzzling behavior as “non-additive.” As Siddhu explained: “Ordinarily, the amount of information coming out from two channels is at most the sum of information that can be sent by each channel. Non-additivity shows us that when quantum channels are used together, they can send more information than each channel sends on its own.”

The Next Steps

To further understand non-additivity, Siddhu wants to look more closely at the role of entanglement. It is possible, he says, that entanglement could boost synergy between two channels, making them more effective at sending information than if the channels were not entangled. In such a case, not only would the channels behave strangely, working better together than separately, but entanglement could increase the efficiency of the transmission even more.

From this analysis Siddhu realized that there was clearly more to learn from the quantum channels and their behaviors with entangled photons. Understanding how quantum channels behave is key to developing and fine-tuning a quantum communication system. Siddhu is hoping to better understand the interactions between these two quantum channels as well as the non-additive behaviors of the channels. With this knowledge, Siddhu and other researchers can work to develop more efficient ways of communicating quantum information and increase understanding of quantum mechanics.

Quantum channels have their own quirks that make them unique to study. In a new paper published in Nature Communications, post-doctoral researcher Vikesh Siddhu of JILA Fellow Graeme Smith's team looked at some of the logistics in using quantum channels to send information. Siddhu analyzed how noise occurring in a quantum channel affects the information it communicates.

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JILA Fellows Thomas Perkins and Graeme Smith win the 2021 Outstanding Postdoc Mentor Award

Steven Burrows — Thu, 16 Sep 2021 20:25:09 +0000

JILA Fellows Thomas Perkins and Graeme Smith win the 2021 Outstanding Postdoc Mentor Award Steven Burrows Thu, 09/16/2021 - 14:25

Kenna Hughes-Castleberry / JILA Science Communicator

Photo of JILA Fellows Graeme Smith and Thomas Perkins

JILA Fellow Thomas Perkins has been awarded the 2021 Oustanding Postdoc Mentor Award. This award recognizes mentors who have gone above and beyond to support their postdocs. Perkins was nominated by postdoc David Jacobson, who praised Perkins' effort to help Jacobson apply and receive the prestigious NIH K99 “Pathway to Independence” Award.

JILA Fellow Graeme Smith also won the 2021 Outstanding Postdoc Mentor Award, being nominated by ��Ҵ�ý�ƽ�� postdoc Vikesh Siddhu and former ��Ҵ�ý�ƽ�� postdoc, Felix Leditzky. Leditzky said Smith “played an integral part in guiding me through the process and helping me achieve this career goal. I aim to pay forward the trust and support that I received from him.”

JILA Fellow Thomas Perkins has been awarded the 2021 Outstanding Postdoc Mentor Award. This award recognizes mentors who have gone above and beyond to support their postdocs. Perkins was nominated by postdoc David Jacobson, who praised Perkins' effort to help Jacobson apply and receive the prestigious NIH K99 “Pathway to Independence” Award.

JILA Fellow Graeme Smith also won the 2021 Outstanding Postdoc Mentor Award, being nominated by ��Ҵ�ý�ƽ�� postdoc Vikesh Siddhu and former ��Ҵ�ý�ƽ�� postdoc, Felix Leditzky. Leditzky said Smith “played an integral part in guiding me through the process and helping me achieve this career goal. I aim to pay forward the trust and support that I received from him.”

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Playing Games with Quantum Entanglement

Steven Burrows — Fri, 20 Mar 2020 17:38:23 +0000

Playing Games with Quantum Entanglement Steven Burrows Fri, 03/20/2020 - 11:38

Rebecca Jacobson / JILA Science Communicator

The Smith Theory Group has found that quantum entanglement could improve our mobile communication systems, allowing them to faithfully transmit more information. Image credit: Steven Burrows / JILA

When you text your friends across the city, you aren’t sending messages directly to each other. Your phones send signals to the nearby cell phone tower, which takes all of these signals and redistributes them to the proper recipients.

This basic setup—multiple senders transmitting to one recipient—is known as a multiple access channel or MAC. And if you’ve had to wait impatiently for the network to send a five-minute video of your adorable cat, you know that MACs have a fundamental limit on how much information they can handle.

As we continue to transmit more data through our MAC networks, scientists are looking to the quantum world to raise those fundamental limits. But before we start building new technology, we need to understand how quantum will work with these MACs.

That is where mathematicians and theory come in. A recent study from the Smith Group used logic games to test how quantum entanglement could improve MACs—and revealed that these communication systems are surprisingly sophisticated.

“The question is, is there a deeper understanding of quantum theory we can gain from studying these (MAC) models?” said JILA Fellow Graeme Smith. “How can we put a quantum overlay on our existing communications networks?”

Shall we play a game?

What do games have to do with quantum mechanics and communication? A lot, actually. Using just paper and pen, mathematical logic games like the magic square game mimic the way a MAC operates, Smith explained.

Here’s how the magic square game works: two players (we’ll call them Alice and Bob) have to fill a three-by-three square—Alice with plus signs and Bob with negative signs—while a single referee decides which row or column they are filling out. Alice needs to have an even number of plus signs in each row. Bob needs an odd number of negative signs in each column.

But there’s a catch: Alice and Bob are separated. You can think of them as being separated by a wall, Smith said. They cannot communicate, which means that one won’t know which column and the other won’t know which row they are filling out at any time.

If Alice or Bob fails, the information is wiped out, which mimics noise in a MAC communication system. Even if our imaginary players agree on a strategy ahead of time, the best Alice and Bob can do is win eight out of nine games, Smith explained.

Getting entangled

In quantum mechanics, particles exist in all possible states at once until you observe them. When particles physically interact with each other they can become entangled. Entangled particles are connected forever, until noise or measurement disrupt them. Whatever happens to one instantaneously affects the other, even if they are separated by great distances.

With entanglement Alice and Bob can peak around the wall. Though they cannot communicate with each other, Alice and Bob can use the quantum correlations to win with certainty, Smith said. Apply that to a MAC and you could create a channel that can handle more data, with much less noise or interference, he added.

Coding for the future

Furthermore, the MAC’s capacity increased regardless of how much entanglement is created. The Smith Group found that even creating a little bit of entanglement can improve the rates on a classical system, i.e. in principle we could apply new quantum tools to our existing communication networks and improve them.

And they also found our classical MACs are more complex than we thought. Mathematicians had believed that without quantum mechanics, it was possible to find single, computable formula that let’s Alice and Bob win the game every time. Smith and his team found that finding a perfect strategy for Alice and Bob is NP-hard—that is, finding a solution would take such an incredibly long time as to be impractical.

This work is just the start. With this knowledge, the Smith Theory Group can start working on finding the limits on coding strategies for these MACS, both classically and with quantum entanglement.

This research was published in Nature Communications on March 20, and was funded by the National Science Foundation Physics Frontier Center grant and the CAREER Award.

Our mobile communication networks are known as multiple access channels or MACS. Through this system, multiple users send data to a single tower, which then relays information to the correct receivers. These MACs have a fundamental limit on how much data they can handle. Through mathematical logic games, the Graeme Smith Group found that quantum entanglement could boost that fundamental limit.

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Quiet Drumming: Reducing Noise for the Quantum Internet

Steven Burrows — Mon, 24 Sep 2018 16:47:30 +0000

Quiet Drumming: Reducing Noise for the Quantum Internet Steven Burrows Mon, 09/24/2018 - 10:47

Catherine Klauss / JILA Science Communicator

Microwave signals are translated to optical signals (red) through a microscopic quantum drum (center). Recently, JILA researchers used strategic measurements of the microwave and optical signals to significantly reduced the added noise. Image credit: Steven Burrows / JILA

But as revolutionary as the quantum computer will be, its promises will be stifled without the right connections. Peter Burns, a JILA graduate student in the Lehnert/Regal lab, likens this stifle to a world without Wi-Fi.

“The regular computer was developed 70 years ago, and it took up an entire lab and could barely do basic math,” said Burns. “It wasn’t until the 80’s that people had the idea to connect multiple computers together, and from that we got the internet.”

Burns is part of a JILA research team hoping to jumpstart the “quantum internet,” or the ability to network quantum computers. These networks would use the uniquely quantum property of entanglement to transfer inherently fragile quantum information between computers. Currently, the development of quantum networks is plagued by noise, but the JILA team recently implemented a new protocol which uses strategic measurements to reduce this impediment.

Fragile Information

Just as it is difficult to build a quantum computer, it’s also difficult to build a quantum network. This difficultly arises from the inherent fragility of quantum information. Even the smallest interference from the outside world, like a warm touch or an observing glance, can collapse quantum properties.

This is why most quantum-computer prototypes are kept inside dilution refrigerators, which are the quantum equivalent of an isolation chamber. Sheltered from the outside world, and ultimately from each other, these computers cannot pass information, “unless you are going to make a really, really big dilution refrigerator,” joked Burns. Instead, researchers are working to translate quantum information into a portable form.

While in a computer, quantum information is stored in microwave signals, which are easy to process, but terrible at traveling. To travel long distances, optical signals are the better carrier. JILA researchers therefore invented a quantum drum to translate quantum information between microwave and optical signals.

The Quantum Drum

Measuring only half a millimeter wide on either side, the drum is comparably sized to a grain of salt. The drumhead, however, is only a ten-thousandth of a millimeter (100 nanometers) thick, which is thinner than most bacteria and viruses. When the drum is excited by either optical or microwave frequencies, “it vibrates at a fundamental frequency,” explained Burns.

This fundamental frequency is the common language the drum uses to translate optical and microwave signals. It does this with the help of “carrier tones”, or additional microwave and optical frequencies which, when contrasted to the signal frequency, differ by the drum’s vibrational frequency. Ultimately, the process is like that of a radio. “There’s one frequency, or carrier tone, that you tune your radio to, and then the actual information [e.g. music or talk radio] is a frequency modulation [FM] on that,” explained Burns.

The drum has successfully translated microwave signals into optical, and optical signals into microwave, with nearly 50% efficiency. But translating actual quantum signals is currently impeded by noise, said Burns.

Noise on the Radio

This noise presents itself as extra photons, which are erroneous packets of microwave and optical energies that wash out the signal photons. These extra photons are produced by the drum itself, as heat and other external energies whisper through the quantum translator. “The problem is, all those extra photons don’t carry any of the information, so you lose your signal in the noise,” said Burns.

Originally, the quantum drum produced nearly 100 extra photons for every translated signal photon. But soon the team discovered that extra photons emerged simultaneously in the optical and microwave signals, like a game of telephone where the malefactor not only throws in extra words, but whispers their misdoings back down the line. By measuring both the microwave and optical signals, the team could identify and remove 3 of every 5 extra photons, thereby significantly reducing the added noise.

While current drum prototypes produce around 10 to 40 extra photons, the ultimate goal is to reduce this number to less than one, said Burns. Realizing this goal will mean that at least some translations have zero extra photons, and the device is ready to translate quantum signals. According to Burns, the team is “very close,” citing only a few minor improvements. This is great news for those not wanting to choose between quantum computers and internet memes.

This work was published in Nature Physics in July of 2018. In addition to JILA graduate student Peter Burns, authors of this work include recent JILA Postdocs Andrew Higginbotham and Nir Kampel, current JILA postdoc Benjamin Brubaker, recent JILA graduate Robert Peterson, current JILA graduate student Maxwell Urmey, and JILA Fellows Graeme Smith, Konrad Lehnert, and Cindy Regal.

Quantum computers are set to revolutionize society. With their expansive power and speed, quantum computers could reduce today’s impossibly complex problems, like artificial intelligence and weather forecasts, to mere algorithms. But as revolutionary as the quantum computer will be, its promises will be stifled without the right connections. Peter Burns, a JILA graduate student in the Lehnert/Regal lab, likens this stifle to a world without Wi-Fi.

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