r/quantum Jan 11 '21

Mod post: User flair, Rule 1

23 Upvotes

User flair is available in the sub, however we've decided to make the "highest level", PhD* & Professor available only as granted on request & verification. Please contact the mods for these. It would be desirable that postdocs use the flair, it should improve the signal-to-noise ratio on the sub.

Rule 1 has been updated to make explicit its practical application: discussion and referral to interpretations is ALLOWED in comments. However, we're not encouraging discussions of the "my interpretation is better than yours" -kind, and comments indulging in it may still be removed. Thankfully, there hasn't been a lot of that going on for some time (years) now. The point is to acknowledge the role of interpretations in "foundational" matters, and also that interpretations are often the approach angle for non-professionals. For posts solely about interpretations, try r/quantuminterpretation instead.

When an answer or a comment focuses or depends on a specific interpretation, it is desirable to make this explicit.

Thank you for your attention!


r/quantum 13h ago

Article A Swedish strategy for quantum technology now in place

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25 Upvotes

On 18 August, the Swedish government unveiled Sweden’s first national strategy for quantum technology. The strategy identifies WACQT, Chalmers NextLabs, and Chalmers’ research infrastructures as national strengths in the field, while emphasizing the need for stronger national coordination in quantum technology, fully aligned with the Swedish Center for Quantum Technology that Chalmers is establishing together with five other universities ... read the full announcement here:

https://www.chalmers.se/en/current/news/mc2-a-swedish-strategy-for-quantum-technology-now-in-place/

u/chalmers


r/quantum 13h ago

Discussion Quantum Mechanics: Change of Basis

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7 Upvotes

This material serves as a bridge from operator formalism to matrix mechanics.
I hope this helps those who are learning quantum mechanics for the first time.


r/quantum 10h ago

Discussion How can a radial node exist within the first Bohr Orbit??

3 Upvotes

I was solving this question and I loved it
(You can try if you want to)

The answer is (2)

The solution is by equation the radial wave function equation to zero, then finding the values of x as 1, 2, 6 and then substituting it in x=2r/a

On solving it we get to know there are 3 possible values of "x" that are 1, 2, 6
which means n-l-1=3
we also know that since at x=0, the value of the equation is not Zero and therefore there is electron probability at the centre, Therefore it's a "s" orbital

so it is obv 4s as it has 3 radial nodes

The minimum distance of the Radial node is a/2 which simply shouldn't be possible right??

Because how can a Radial node or probability of electron be Zero before the "first Bohr orbit" that is 1s

The solution a/2 means there is a radial node before the 1s orbit, But how can a node or 4s exist before 1s? It will face shielding and we all know 4s is an outer orbital and it also has higher energy

I would love if someone could solve this doubt of Quantum Physics


r/quantum 1h ago

Question William James + Henri Bergson + Carl Jung + Erwin Schrödinger + David Bohm + Itzhak Bentov + Roger Penrose + Jacobo Grinberg + Federico Faggin = ?

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Upvotes

r/quantum 19h ago

Discussion Proving the Cl2 bond length with the LCAO method

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6 Upvotes

Any thoughts?


r/quantum 1d ago

Article How do you measure one third of an electron?

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3 Upvotes

An electron is supposed to be indivisible. It carries one fundamental unit of electric charge, and every electron is exactly the same.

But under extreme conditions, large numbers of electrons act together and give rise to new quantum objects called quasiparticles. These act as if they carry only a fraction of an electron's charge, making them one of the strangest phenomena in modern physics.

u/EPFL researchers have developed a graphene device that measures the tiny, fractional electric charges carried by some of the strangest objects in quantum physics.

Read the full article: https://actu.epfl.ch/news/how-do-you-measure-one-third-of-an-electron-4/


r/quantum 2d ago

How should I begin learning an introduction to quantum physics?

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3 Upvotes

r/quantum 2d ago

Can someone please explain me quantum entanglement!

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0 Upvotes

r/quantum 2d ago

A new way of doing Quantum Chaos ?? https://www.mdpi.com/3533324

0 Upvotes

Am I right if I say that this paper proposes a new and much less laborious way to experimentally test whether the device under study behaves in a quantum way or not. It could be used with electrons or any spin-1/2 fermion, or even with photons if we use horizontal and vertical polarizations... And it's interesting how a Quantum Walk, diffusive by nature, ends up localized in scars (for certain values of the original parameters). It is also a quantum chaos model that doesn't originate from a classical Hamiltonian of a chaotic system that is subsequently quantized...


r/quantum 3d ago

Quantum entanglement

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1 Upvotes

r/quantum 4d ago

Schrödinger’s Equation for Dummies — Part II: Decoding the Equation

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5 Upvotes

r/quantum 5d ago

Question Next book after reading Quantum Mechanics - The theoretical minimum by Leonard Susskind

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4 Upvotes

r/quantum 6d ago

Trying to learn!

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20 Upvotes

r/quantum 6d ago

Question Question inflaton

0 Upvotes

Selon la théorie d’un multivers inflationnaire,dans laquelle des « univers-bulles »naîtraient dans notre univers, la masse de ces univers ne devraient pas courber l’espace temps ? Je ne suis pas un pro de physique donc restez indulgent dans vos critiques svp


r/quantum 7d ago

Question about the state construction in Khrennikov's DCM

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2 Upvotes

r/quantum 7d ago

want help / suggestions on my quantum portfolio im trying to diversify! please read and help:)

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0 Upvotes

i am trying to invest in purely only quantum because im just a freak and want to have no diversity besides diffrent quantum company’s.the upside is just to high and im young i got nothing to lose if i invest a lot into something that dont work out shit happens im willing to take the risk. i like post quantum stocks like arqq and btq but haven’t bought in yet and want to know what others think about stocks like INFQ ARQQ & BTQ or other suggestions they might have. i like pick and shovel’s approach towards quantum as well so anything you think could be the next play just let me know. im strictly only in IONQ LAES and QBTS right now but really want to diversify. im in college coming up at 21 years of age and make decent money on the side so it don’t necessarily haveh to be cheaper stocks .


r/quantum 8d ago

Discussion Quantum Mechanics: Ladder Operators and Matrix Mechanics

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46 Upvotes

This material covers the algebraic formulation of ladder operators and their explicit matrix representations through detailed examples.

Correction for Page 48: An imaginary unit 'i' was inadvertently omitted during the derivation of the momentum operator. The corrected equation should read: a† - a = -i * √(2 / m ħ ω) p

Due to the strict 10-image upload restriction on Reddit, the subsequent mathematical solutions and the final substitution step have been truncated. I apologize for the abrupt conclusion of the document.


r/quantum 8d ago

Is zettili a good start for undergrad QM-I?

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1 Upvotes

r/quantum 8d ago

Question Petite question de physique quantique

0 Upvotes

J’ai une question : si on envoie une particule intriquée à une autre particule au delà de l’horizon des événements d’un trou noir, que devient l’autre particule ? Est elle affectée ?


r/quantum 9d ago

MS in Quantum Technology

8 Upvotes

I completed my BTech in Engineering Physics and have been working as a Data Scientist for 1 year. I’m interested in quantum physics and now want to pursue an MS in Quantum Technology/Quantum Computing.

I have an AI research project and am currently doing a self-project on quantum state preparation. I’m not sure if my profile is suitable for this field.

Could you suggest some good, moderate/reachable universities in the UK, France, Germany, Netherlands, or elsewhere where I’d have a fair chance?


r/quantum 10d ago

EdX course on undergraduate quantum mechanics that closely follows Quantum Mechanics Done Right

30 Upvotes

Starting August 22, the same undergraduate course as the one offered at Georgetown University will be available on edX. It is an instructor led class, and I am the instructor. It is an 18 week course. While the official prerequisites do require calculus and linear algebra, the course itself does not use very much of this, so if you have a strong high-school math training you should be able to work through it, especially if you use the alternative treatment in Quantum Mechanics Done Right for topics that use calculus. It teaches quantum mechanics in a representation-independent form, emphasizing operators and states and is a spins-first, photons-second curriculum. If you join the class, please be sure to send me a note in the forum discussion. The class is free for auditors, and charges a modest fee (when compared to Georgetown tuition) for a certificate. I will be participating in the course throughout the full 18 weeks unlike most MOOC instructors. I am also adding suggested problem sets for auditors in this run of the course. To enroll, go to https://www.edx.org/learn/quantum-physics-mechanics/georgetown-university-quantum-mechanics


r/quantum 10d ago

Discussion Every Possible Baryon (A book I wrote)

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0 Upvotes

r/quantum 11d ago

Discussion Quantum Computing PhD in China

10 Upvotes

Hello everyone! I just graduated with a Computer Science degree currently I have one published paper in AI and two in quantum computing currently in the publishing process. I have also done a math thesis project on relativistic quantum mechanics and TAed QC courses multiple times.

Now, I have heard that it is not possible to jump into a PhD directly with this kind of background since the pool is very saturated right now. However, I have heard that china is doing a great work in the field and that some of their PhD programs in QC are really good. Is that true? and would you recommend it? most European programs require a masters program and I do not have the funds to go into them without a full scholarship which are very scarce for international students (already got rejected too much from the US).

I would love to hear your thoughts!


r/quantum 12d ago

What would it take for APDs/SPADs to be viable in photonic quantum computing? Architecture redesign vs. device-level breakthroughs!!

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0 Upvotes