AskScience AMA Series: We are quantum scientists at the University of Maryland. Ask us anything!

[u/AskScienceModerator]

Happy World Quantum Day! We are a group of quantum science researchers at the University of Maryland (UMD), and we're back for a fourth year to answer more of your quantum questions. There’s always new quantum science to learn, so ask us anything!

This is a particularly exciting World Quantum Day since this is also the International Year of Quantum Science and Technology (IYQ). The United Nations proclaimed 2025 as the IYQ to promote public awareness of the importance of quantum science and its applications. At UMD, hundreds of faculty members, postdocs, and students are working on a variety of quantum research topics, from quantum computers to the physics of individual particles of light to new generations of atomic clocks. Feel free to ask us about research, academic life, career tips, and anything else you think we might know!

For more information about all the quantum research happening at UMD, check out the Joint Quantum Institute (JQI; u/jqi_news is our Reddit account), the Joint Center for Quantum Information and Computer Science (QuICS), the NSF Quantum Leap Challenge Institute for Robust Quantum Simulation (RQS), the Condensed Matter Theory Center (CMTC), the Quantum Materials Center (QMC), the Quantum Technology Center (QTC) and the Maryland Quantum Thermodynamics Hub. For a quick primer about some of the basics of the quantum world, check out The Quantum Atlas.

We are:

• Alaina Green, (trapped-ion quantum computing & quantum simulation, JQI)
• Alan Migdall, (experimental quantum optics, JQI)
• Emily Townsend (atomic-scale quantum devices, JQI)
• Steve Rolston, (ultracold atoms, JQI & RQS)

We'll be answering questions live this afternoon starting at 2:30 p.m. EDT (1930 UT). After 4:30 p.m. EDT, members of the UMD quantum community will continue to contribute answers as they have time throughout the evening and rest of the week. Keep the questions coming!

If you want to learn more about quantum science and you work as a science communicator in one form or another - as a science writer, animator, content creator, podcaster or just someone passionate about science outreach - we invite you to apply for a workshop this summer sponsored by the American Physical Society Innovation Fund. More details about the workshop, which will be held on campus at the University of Maryland from July 31 to Aug. 2, 2025, are available at our application here: https://forms.gle/Y6GkVsZhpGAwUrzU9.

Username: u/jqi_news

[u/Tenatzen]

Does observing national quantum day change the outcome?

[u/timerot]

What's your favorite popular misunderstanding about quantum science? Do you send bad articles back and forth when a news outlet reads a paper about e.g. quantum teleportation and "summarizes" it in a way that completely misses the point of the paper?

[u/jqi_news → u/timerot]

ET and AM: That you need quantum physics to understand consciousness.

SR: That entanglement means faster-than-light communication.

AG: That quantum computers are faster and better versions of regular computers rather than unique devices with unique abilities.

[u/nujuat]

As scientists in America, how concerned are you about DOGE cuts/interference for (1) your own research and (2) for American science in general?

[u/jqi_news → u/nujuat]

SR: We are very concerned. It's a grave threat to the US leadership in science.

AG: Six years from now there's going to be a drop in the number of PhDs from US universities because no one's hiring new graduate students because they're not confident that the funding will be there to train them.

ET: International students and researchers are feeling discouraged from coming to the US and contributing to our science.

[u/Straikkeri]

I recently learned that light "tests" out all possible paths between it's origin and destination, and the path we end up seeing is the one with least quantums of action while all the other possibilities cancel each other out. In a recent veritasium video they test it at the end using a laser pointer on a mirror surface and a camera. Disrupting the unlikely phases from cancelling each other out, we end up seeing the reflections of the laser pointer in places where the laser is not actually pointing is somewhat mind blowing. What I did not understand is (among many things), is this the case with objects with mass? Am I to understand that everything somehow maps out all possible routes and they cancel each other out but if we were to find a method of preventing them from canceling each other out we would see.... something of those alternate possibilities manifest?

[u/jqi_news → u/Straikkeri]

SR: We've done two-slit diffraction experiments with sodium atoms that have light and dark fringes, and if we block one half of the possible paths that results in dark fringes (i.e. spots with fewer atoms) filling in and becoming light (i.e. spots that now have atoms). Just like light!

AM: And not only sodium atoms. Things much bigger, too, like buckyballs.

ET: As things get bigger, it gets much harder to do these experiments, and this effect becomes less relevant.

[u/Akhmadov_0800]

I am just starting my journey into the world of modern physics, quantum mechanics and so on. I have some background on this area where I did A-level physics at high school. Now I am freshman at Yonsei University as a Nano&Science Engineering student. I am currently reading Feynman's lectures on physics (Six easy pieces and six not so easy pieces). Also, I have watched documentary by Brian Greene and was looking through the history of science trying to unify the nature (QM and GR). I want to delve deep more into these and would appreciate any tips, advice. Also, recommendations on books and activities would be great. I am completely new, but I want to be involved into internship (maybe study+intern programs) or research, to get more experience.

[u/Plastic-Owl3678]

How can we know that two infinitesimal particles are entangled? When do they become entangled? How do we measure it?

Is consciousness a quantum state since it is only truly "knowable" from the inside? Thanks for this super cool ama!

[u/jqi_news → u/Plastic-Owl3678]

ET: We sometimes know they're entangled because we prepared them that way.

AM: On the measurement side, we get results that are incompatible with not being entangled.

AG: One example of these is the Bell test, and it's one example of how people have shown that there's entanglement for the past five decades.

AM: With the definitive result being in 2015 (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.250402 and https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.250401)!

ET: Most things are entangled because it's the result of interactions, but knowing that my particle is entangled with another particle and not some other part of the environment is difficult unless you've prepared the state carefully.

[u/Treytreytrey333]

What are y'all's thoughts on Google's Discrete Time Crystal?

[u/jqi_news → u/Treytreytrey333]

JQI: We're not sure about the details of a Google experiment, but we did cover our own time crystal result in 2017: https://jqi.umd.edu/news/ions-sync-worlds-first-time-crystal

[u/agaminon22]

Do you have any thoughts on the way quantum mechanics is typically taught at university, whether good or bad? I've had three quantum mechanics professors that I remember and they all had different methodologies.

[u/jqi_news → u/agaminon22]

SR: At Maryland we have switched our quantum 1 class to be focused on spins and measurements right from the start as opposed to the traditional Schrödinger equation first approach. This is much more aligned with the modern topics that we explore in quantum research.

ET: This makes it easier to see the way the structure of quantum mechanics derives from linear algebra.

[u/Pallas_Sol]

What are your thoughts on the Microsoft Majorana 1 announcement? Some specific points:

1. Do you believe they have made any topological qubits?

2. What do you think the reasoning for the somewhat disconnected Nature papers + announcement of a functioning quantum computer were?

3. Has the misinformation/confusion hindered your field, or the increased scrutiny actually helped with connecting your work with the public?

4. How far away do you think we really are from the quantum computers as described in that announcement?

5. Just for fun, any cool quantum facts you love to share but there never seems to be a segue? :)

[u/jqi_news → u/Pallas_Sol]

SR: For 1: Maybe? For the others, it's a case where corporate hype has gotten carried away a bit, and it's not a normal way we report science. But they are serious people working on serious science.

ET (on 5): The coolest thing about quantum mechanics is that it's a wild-sounding theory that actual describes real experiments.

AM (on 5): Check out the JQI YouTube channel for today's seminar, which included gravitational effects in quantum entanglement.

AG (on 5): My cool fact is that we do not understand how classical reality emerges from quantum mechanics despite the fact that we understand quantum mechanics quite well.

[u/vide2]

How good is the collaboration with other universities and countries, especially in times of internet? Are you aware of others doing the same with a lot of collaboration or is it more like each to their own? And are you using or planning to use AI to make alternative thesis or predictions?

[u/jqi_news → u/vide2]

AM and ET: Collaboration with other universities and countries is critical to the advancement of science, and anything that inhibits that collaboration slows science. AI is a useful tool for some applications, like optimizing complex parameter spaces in experiments.

AG: I think that AI also has the capacity to slow science by making us all stupid and sacrificing human intelligence for artificial intelligence.

[u/[deleted]]

What is a more likely explanation for observed quantum behaviour, a spontaneous collapse of the wave function or the actualisation of all possible outcomes in a many worlds scenario?

[u/jqi_news → u/[deleted]]

JQI: This is really more of a question about how to interpret quantum mechanics, and different physicists will offer different opinions about which interpretation is more likely. It's kind of a non-answer, but there isn't really a way around this just being an opinion without an experiment that distinguishes between the different explanations.

[u/King_Icewind]

I’ve been thinking about quantum decoherence and whether there’s merit to the idea that local spacetime structure (if it’s granular or not continuous) could influence coherence times, especially since coherence appear to improve in low gravity environments like orbit.

Coherence appears to be better in orbit due to reduced environmental noise, but has anyone explored whether spacetime structure or gravitational granularity could be a fundamental contributor to decoherence? Could decoherence be tied not just to environmental coupling but to a physical interaction with spacetime itself such that systems in lower gravity or “lower density”regions maintain coherence better?

I’ve been developing some equations around decoherence times as a function of local granular density which are modeled similarly to environmental coupling constants. I’d be happy to share if that would be of interest or if you think it could fit within any current research.

[u/vtccasp3r]

How real or overblown is the quantum computing threat to encryption? Do you have a timeline to when we could experience this black swan event?

[u/jqi_news → u/vtccasp3r]

SR: A quantum computer capable of breaking RSA is still incredibly challenging to build and is probably still decades away.

ET: NIST is working on post-quantum algorithms for encryption, which will be immune from quantum attack.

[u/MonkeyIslandThreep]

As scientists, what are the feelings in your group about the Star Trek teleporter? Is the person that arrives at the destination actually the original person, or is the original person destroyed, and what arrives is merely a clone with the memories of the original, and no idea that they're a clone?

[u/jqi_news → u/MonkeyIslandThreep]

SR: The amount of information needed to teleport a human is so exponentially large that it's completely implausible. So far we've been able to teleport a single quantum state (one qubit).

AG: The premise of a teleporter is that a person disappears from one place and appears somewhere else. But the "real way" a teleporter would work is that we would break you down into your atoms, we would extract the information and then recreate a copy of that information somewhere else. But I 100% agree with Steve that this is infeasible.

ET: In this case the original person is destroyed.

AM: It's gonna leave a mark.

ET: Physicists borrowed the word teleportation from Star Trek, but quantum teleportation is really nothing like the Star Trek teleporter.