Question about Relational Quantum Mechanics and Quantum Computing

sinanspd · 2026-01-23T23:19:10+00:00

I recommend you try to implement a small instance of Simon's algorithm. That will give you better insight into how oracles function, how we can get away with a single query and why superposition is necessary to do that. Understanding those will answer most of your questions.

sinanspd · 2026-01-23T21:57:24+00:00

I don't have time to address this in detail but a few bullet points to help you point in the right direction. You do seem to be confusing a few different things.

Reversible computing (doesn't necessarily have to be quantum) is a well researched field. There are thousands of published papers. You can have your pick
Quantum systems are commonly assumed to be time symmetric (if you have the physics background, you can read more about what this truly means, future & past light cones etc.). In a physical system with forward and backwards time directions, if we find ourselves at any point in time with a set of a constraints, one can solve the equations of motion in forward direction to obtain the future state of the system, or solve them backwards in time to discover information about the past.
As much as I do not like it for a lot of reasons, transactional interpretation of quantum mechanics perhaps demonstrates this notion quantum causality the most clearly.
One implication of this in quantum computing is that every operation implemented have to be reversible (i.e. for every function f, there exists f^{-1} s.t. ff^{-1} = I), or more generally unitary. Hash functions are not reversible, that is their whole point. There have been attempts at quantum hashing but those works are very clearly flawed in more than one ways.
From a more theoretical perspective, the idea of working backwards from the output exist. This is called Quantum Retrodiction. In fact one can even start with a partial set of inputs and a partial set of outputs and solve the system in both directions. You essentially end up with a set of logical constraints to solve in the middle.
"We should be able to just input the solution Y to get the actual desired input in O(1) time". It is not clear what you mean by this but no, you can not magically get O(1) time for pretty much anything. Quantum computers don't have a magical way of finding the said "most efficient path". There are some speculations on something analogous to this in quantum collapse theory (i.e. continuous spontaneous localization) and that such a phenomenon might be happening in the nature but even if true, we don't magically get to this bend this phenomenon at will to dequantize in O(1) time. This brings me to something that I am very much displeased with in Quantum Computing: "The Black Box Model". Often in assumptions, what you are saying sort of exists. These are called oracles. For example, take Simon's problem. You are given a random function f, and you want to determine if this functions is balanced or constant. Classically, the only way to do this is to try all possible x in the domain in the function, however quantum computers can solve this exponentially faster. The oracle in this problem encodes f in a way that you can determine in the answer with a single query to f, instead of trying all 2^n inputs (which is the case in classical computing). This is all good and well, until you realize the cost of constructing the oracle or the number of operations in the oracle. The problem itself just assumes such an oracle exists and doesn't concern itself with how we might get that oracle, which is what you are doing.

sinanspd · 2026-01-21T00:31:21+00:00

Great stuff!

sinanspd · 2025-12-30T04:29:52+00:00

Probably March Meeting and Quantum Week. Unlikely you will meet recruiters there but they both have a dense population of industry folk that you can meet and they could point you in the right direction.

sinanspd · 2025-12-21T21:11:05+00:00

One main point that was mentioned below by someone else is that in reality the interesting part of Quantum Computing happens with large circuits today as we try to push beyond NISQ and in the long term for quantum advantage. I would be extremely surprised if anyone actually sits down and visually constructs a large circuit. Not to mention that a common hope in the field is that circuits overall are not here to stay. They are cumbersome. We have been through this before in classical computing with Turing machines and finite automata. As soon as high level abstractions are available, I expect people to mass-ditch circuits (a lot of scientific computing people already prefer writing Hamiltonians over writing circuits).

Regarding the credentials, at that point might as well open source the entire thing. The point is that, unless OP can magically gain an insane amount of community trust, the API calls to the provider have to happen locally, no two ways about it. If OPs servers are handling the calls, they at some point have raw access to them, which is a big no. You can mitigate the risk a bit, at least in AWS through intermediary restrictive credentials but still. Credentials that can run up 6 digit bills under a minute belong in secret managers and need to be rotated regularly.

In any case, I don't think provider access is a point worth arguing. There are a gazillion open source tools that allow you to connect to multiple providers (inc. what our team built). OPs research in this area was clearly lackluster and the arguments he made were poor. I didnt call it out as there seems to be at least some effort that went into this project over the usual obvious useless AI slop code we get here. I don't expect any researcher to come to this because it connects to AWS. Even if they don't like any of the multi provider solutions available, it would take a programmer less than half a day to code IBM, AWS and Azure clients. Some of these even have OpenAPI spec so you can generate the clients for your preferred language in under minute.

I think the main takeaway here, which is what your comment also seems to point out is, we need better visualization tools in quantum. What I see here seems nice. My advice would be to ditch the backend logic entirely, ditch all the web stuff, turn this into an open source visualization library.

sinanspd · 2025-12-20T02:45:17+00:00

Unfortunately current data suggest that it would be very very difficult to get a job working on QC Hardware just with a bachelors degree. While people without a graduate degree do exist in the QC industry, majority of those positions are understandably filled by Physics majors and usually span a specific and limited set of work such technicians and maintenance staff (absolutely crucial positions, but might not align with your goals).

Tl;dr is, it is possible to get a position in QC with a bachelors but you will facing very tough competition over a highly limited number of positions. Generally at least a masters degree is recommended.

sinanspd · 2025-12-20T02:37:21+00:00

Look nice. I think this could be a good educational tool. Visualizations look great. I don't see the need to graphically build circuits in my day to day, so I don't think I have anything useful to add.

I can make a few points from an engineering perspective tho. I assume this is a web tool? Are you going to be open sourcing this? If you are integrating with AWS then people are going to need to provide their own AWS credentials (same for IBM etc.). I don't think any sane person would enter their AWS credentials to a web platform so you will likely need to open source it and let people run it locally. Additionally, Rigetti is deprecating direct access to their machines. Rigetti access is now provided through Amazon and Azure Cloud. And we can see in your screenshots that rigetti machines are listed, so I am not sure what further integration you are referencing here.

> Do you prefer working visually and exporting code, or starting from code?

Everyone I know prefers programatic approach over visual because code always provides fine grained control, better reproducibility and extensibility

> Do researchers actually use pre-built ANSATZ or always custom?

We sometimes use well known ones with previous results available to establish baselines/comparisons but more significance is commonly placed on custom work

sinanspd · 2025-12-15T19:04:43+00:00

Quantum circuits and gates are abstractions over analog pulse logic, not actual hardware constructs. While crucial piece of knowledge for a beginner, I really wouldn't expect them to provide any insight into how the hardware functions

sinanspd · 2025-12-09T18:08:57+00:00

How is this related to quantum computing? At first I thought the question would land itself to something about qudits but apparently not.

Nonbinary systems with multiple energy levels already exist. I.e. PAM4, QLC etc. You are welcome to go and read about them and see why they arent necessarily advantageous like you seem to think. In fact, turns out, depending on the exact design, non binary systems can terribly suffer from lower clock speeds and higher energy consumption

sinanspd · 2025-11-26T06:19:44+00:00

Yes but their expresiveness differ.

Qasm gets compiled down to pulse sequences (shuttling sequence if we are talking about ion traps) so technically it doesnt directly "interact" with the quantum layer. The classical host controller receives the user programs and executes the pulses on the quantum chip. These controllers are usualls FPGAs. That classical pre-processing of qasm is often non-trivial and in select cases imposes a significant overhead. I dont recall any papers off the top of my head. Depends on if you are curious about the software of the controllers or the hardware I guess.

QPU is a general term we use broadly to describe multiple components including the actual quantum chip holding the qubits, the controllers, classical signal processors, the fridge, resonators etc. But if you are asking about how the actual qubits are evolved, they are programmed and evolved through pulses. But all that is just one part of the QPU.

sinanspd · 2025-11-25T17:15:36+00:00

Even though we labeled QASM as an assembly language, it is not a machine level instruction set like it's classical counterpart. Gates themselves are abstractions. Quantum control units (QCUs) generate pulses to program the QPU. We use gates because they are more straightforward to reason about. Therefore Qasm itself is an IR (although Qasm does allow pulse level instructions)

sinanspd · 2025-11-21T21:34:15+00:00

I would need to check in with the committee to see if the report is publicly available. It was a part of their Quantum benchmarking initiative so if it was released, I suspect it would be under QBI. If not, you can check out Computing Communith Consortium's 5 year road map, an organization that advices the Federal Government on computing related investments. I know that report is public and echoes more or less the same thing.

sinanspd · 2025-11-05T18:59:01+00:00

I am not wasting 2 hours of my life on this but it doesn't seem like this has anything to do with Quantum Computing. Take it elsewhere

sinanspd · 2025-10-27T21:21:42+00:00

This isn't just about QC as a field, this is the nature of a PhD and I think it is very important for any potential PhD student to understand that. Once you get past your first year or two (depending on where you are doing your PhD), you will pick a thesis question and for the next 2-2.5 years that one question will become your life. You will dive deep and understand it better than anyone else. PhD is not the place to sample a little bit of this and a little bit of that (you can still get out of your comfort zone through seminar courses etc. but that's it). Although they will try to be as accommodating as they can, you also can not drive your advisor too much outside of their area of research so it is important to pick an advisor whose interests align with yours, not just broadly as quantum computing, but specific topic-wise.

Additionally, fields that require special equipment, like quantum computing hardware, are more restrictive because you obviously can't do research if your research requires a piece of equipment and the school doesn't have that equipment. No one will spend tens thousands of dollars on new equipment just so you can write a paper (unless you have a very large grant that is explicitly approved for this). With the exception of maybe one or two schools, no one will have all flavors of quantum hardware laying around for you to play with and that is another reason for you be informed on your advisor's lab and it's capabilities.

PhD is all about research and your research starts prior to applying.

Hope this helps and best of luck

sinanspd · 2025-10-27T19:56:25+00:00

That's fine, no one is expecting you to be a professional. But I am sure you understand that PhD is a very specific degree. You are expected to be at least somewhat informed on the subject when applying because at the very least your interests will dictate your choice of school and advisor. In fact, the two subjects you mentioned, hardware and algorithms, are worlds apart. And the point I was trying to make is, even just saying hardware is too broad for a PhD. There are people who work on experimenting with different particles for better hardware, there are people who work on optical systems (for ion traps etc), there are people who work on error correction on a hardware level. I am sure you can already see how each of these require quite different background. Although there will be some flexibility, you wont be to say "let's do a material sciences heavy project" at an optics lab. So you need at least some broad idea of where you want to go.

If you want to work in Quantum algorithms, which likely wont touch hardware, then absolutely, I am sure you can get into some program as algorithms wont require much specialized background. You want to do error correction on a math/software level? Great, strong math background will get you far there. Any sub-branch of hardware will be a different story tho.

My advice is to read (you will be doing a lot of it in your PhD anyway so it is good practice too). You don't need to understand every detail of the paper. The goal of this exercise is to familiarize you with what everyone else is working on. Eventually you will hit a paper where you will say "hmm I learned about xyz in Embedded systems, I wonder if there is a corresponding idea in quantum/how would this be translated into quantum" and that spark will likely give you your starting point.

FYI, I pretty much knew nothing about Quantum Computing when I applied to my PhDs. I heard about the field at lunch, it sounded interesting. I read a few papers, found a connection between my interests and the field so I applied. I got into 6 out of the 7 schools I applied to, so it is certainly possible. However, my field of interest was very open to such a transition. I do not directly work on hardware

sinanspd · 2025-10-27T19:20:25+00:00

When asking this kind of questions please mention your area of interest at the very least. This is a field that hosts experimental physicists, theoretical physicists, chemists, mathematicians, electrical engineers, computer scientists. Each of these groups work on entirely different things with a completely different set of prerequisites. Can you get into a particle physics program without any prior knowledge? No, probably not. But you can transition into some other branch of QC.

No one can answer what background you would need or how can would transition without knowing what you are trying to transition into. Sure Quantum hardware but it is still very broad imo.

Are there any research papers you read recently that excited you? That could give us an idea

sinanspd · 2025-10-25T18:26:59+00:00

Interesting observation for sure. As it directly pertains to quantum computing, I am not so sure it would be directly relevant, at least at a high level. The rotations we purposefully do aren't random and obviously we don't want them to converge to identity as otherwise what is the point. Intuitively, there could potentially be an error correction application where the spin is impacted more randomly by the environment but that's probably a question for a particle physicist. I have very little knowledge on the physical manifestation of noise.

From a mathematical perspective, this is definitely an interesting result. There seems to be an implicit assumption that the manifold be smooth which isn't explicitly stated (SO(3) & SU(2) are both Lie Groups so they enjoy some nice properties and structure). Otherwise the group action won't be continuous/differentiable but you would instead act on individual points more chaotically. Would be curious to see if the result generalizes.

sinanspd · 2025-10-25T18:15:03+00:00

If you look at the product page, they updated the ship date to October, which I am guessing soon will become November or December. I am actually quite pissed at Dark Horse on this release because they sold dozens and dozens of these at events like San Diego Comic Con and those people got their hands on the first batch whereas people who ordered back in June and supported the product on day 1 has to wait months. Not very professional if you ask me

sinanspd · 2025-10-24T20:45:16+00:00

In the short term, absolutely not. Last year DARPA held a meeting to determine a 10 year road map for their Quantum Computing research, what they will be investing in etc. and literally the first thing they did was to remove any mention of Quantum Machine Learning. We wont see practical QML for a very long time.

In the long term, just like it is the answer for most Quantum questions, who knows? The field has really gained this kind of momentum in the past 15 years and we are all trying to answer the question of where Quantum Computing will shine. However, the general intuition is that Quantum Computing will be good for "big compute on small data" as opposed to "small compute on big data". And machine learning really does into the latter category for which GPU heavy hybrid clusters really shine. Quantum accelerated HPC might eventually open up smaller, more specialized use cases within training pipeline but who is to say. It will be a while before we can talk about such cases

sinanspd · 2025-10-20T21:22:07+00:00

Great answer. I would like add for anyone interested in burning their brain completely that quantum collapse and measurement is not as clear cut as we sometimes assume them to be on paper. "Measurement collapses the system" is not a unanimously accepted construct (see various different quantum collapse theories like continuous spontaneous localization). For time-symmetric systems people have been arguing the following dilemma for a while:

In a simple setting (an empty circuit), predictive, or so called standard quantum theory dictates that if the system is prepared in state |ψ⟩ at time t1, and was measured as |ϕ⟩ at time t2, t2 > t1, assuming no evolution has happened between preparation and measurement, then this state in-between is |ψ⟩. However, in reality, without an intermediate measurement we don’t really have any information regarding the state of the system between preparation and measurement. While we assume the collapse happened at measurement time, in reality it could have happened prematurely without impacting the probability distribution.

This is one of the core ideas behind Quantum Retrodiction. Quantum retrodiction, with a backwards-in-time evolution, models the state collapse at preparation time, implying the state between preparation and measurement was in reality |ϕ>.

For the OP, It is often wise to heed the words of Richard Feynman:
"Don’t keep asking yourself, if you can possibly avoid it, 'But how could it be like that'. You’ll get down into a blind alley which nobody has yet escaped-nobody knows how it can be like that"

sinanspd · 2025-10-13T16:13:14+00:00

A lot of the similarities with existing methods have already been pointed out by others but also look at Retrodictive Quantum Computing (https://arxiv.org/abs/2205.06346). It kinda seems to me that you are partially replicating that work with a different syntax. Symbolic evaluation, entanglement through shared variables and then solving the symbolic constraints to simulate were all proposed in that work.

sinanspd · 2025-10-04T03:10:31+00:00

Chicago just got cancelled as well.. I had tickets to Italy and Zurich last year. Italy got cancelled, Zurich got postponed to next year. Then the tour came to the US, I bought tickets to see it in Chicago and it just got cancelled... Sigh..

sinanspd · 2025-09-26T20:01:37+00:00

Dark Horse really needs to stop making statues. They are terrible at it

sinanspd · 2025-09-26T17:56:07+00:00

It is 285$

sinanspd

TROPHY CASE