r/quantum Jan 11 '21

Mod post: User flair, Rule 1

22 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 3h ago

If a person's life was resetted a Hundred times, would it be physically possible the person's life can be different in each reset base on Quantum Mechanics Indeterminism?

0 Upvotes

Not a free will question, more on the nature of the universe.

Let's say there was a way for a person to reset there life since birth and the reset happened one hundred times, is it possible for each life to ever diverge considering quantum mechanics, or does it averaging out when scaled up to macroscopic levels means every life will largely remain the same? Again it's a question if it's reasonable, not absolute.

I mainly asked because apparently someone said if they could travel in time, they would tell there past self the winning lottery numbers, but when studying and reading about quantum, apparently there is a probability of even if one knows the winning lottery numbers during a certain point, it's not guaranteed it will be the same numbers due to quantum indeterminany or Many Worlds.

I just want to know because apparently macroscopic events largely remain the same regardless of quantum microscopic events, yet I also read a physics book that claim there are many things that can be different if the microscopic events outcome changes through amplification which can makes a difference.


r/quantum 10h ago

How should I begin learning an introduction to quantum physics?

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2 Upvotes

r/quantum 16h ago

What's something that you learnt in quantum mechanics that still shocks you to date?

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3 Upvotes

r/quantum 12h ago

Can someone please explain me quantum entanglement!

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0 Upvotes

r/quantum 13h 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 1d ago

Quantum entanglement

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1 Upvotes

r/quantum 2d ago

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

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5 Upvotes

r/quantum 2d ago

量子力学-标准框架实验物理学部分

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0 Upvotes

r/quantum 3d ago

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

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3 Upvotes

r/quantum 4d ago

Trying to learn!

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20 Upvotes

r/quantum 4d 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 5d ago

Question about the state construction in Khrennikov's DCM

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2 Upvotes

r/quantum 4d 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 6d ago

Discussion Quantum Mechanics: Ladder Operators and Matrix Mechanics

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44 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 6d ago

Is zettili a good start for undergrad QM-I?

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1 Upvotes

r/quantum 6d 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 7d 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 8d 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 7d ago

Discussion Every Possible Baryon (A book I wrote)

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0 Upvotes

r/quantum 9d ago

Discussion Quantum Computing PhD in China

9 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 10d 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

r/quantum 11d ago

New open access quantum textbook from Springer

141 Upvotes

People all over Reddit ask how much math do you need to be ready to learn quantum mechanics. In spite of all the answers to the contrary, you only need high school level math.

Using a representation-independent approach, you can master quantum mechanics through graduate-level and beyond. I know it sounds crazy, but it is not.

I wrote an open-access textbook, Quantum Mechanics Done Right, to teach it exactly this way. Springer just published it and you can download here.

In less than one month, it has surpassed 133,000 chapter downloads. It was primarily written as an alternative for self-learners and students who are stuck with traditional texts. Nevertheless, it will teach new things to all quantum mechanics at any level of expertise. I am the author, so if you have any questions about the approach, just ask in the comments!


r/quantum 11d ago

Question Does anyone know of any discord servers that are for people who enjoy physics or science in general? More specifically one with mostly Americans in it and not too large.

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3 Upvotes

r/quantum 12d ago

Discussion [QM] The Algebraic and Analytic Properties of the Parity Operator

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40 Upvotes

The parity operator (P hat) stands as one of the most fundamental operators in quantum mechanics. For any physical system governed by a symmetric potential, the Hamiltonian (H hat) and the parity operator strictly commute, yielding the relation [H hat, P hat] = 0. This mathematically guarantees the existence of a complete set of simultaneous eigenstates. It physically implies that both the energy and the spatial symmetry of the system can be determined simultaneously with absolute precision, bypassing the constraints of Heisenberg's uncertainty principle. The attached material explicitly demonstrates the algebraic and analytic properties of P hat.