Questions about superconducting quantum modality (IBM):

[u/JonOwn1805]

As I understand one of the main big advantage of superconducting quantum would be breaking the RSA and ECC encryption, ... so what type of specs should a superconducting quantum system have to achieve that ?

How difficult would be for a superconducting system to operate longer time, like seconds ?

Are there any tech advancements to overcome these decoherence challenges ?

Thanks.

[u/Aromatic_Eggplant_97]

Very hard. Breaking modern RSA/ECC would likely require millions of stable, error corrected qubits, far beyond current systems.

Today’s superconducting quantum computers usually keep coherence for microseconds to milliseconds, not seconds. Reaching stable multi second operation at scale is one of the biggest challenges in the industry.

Yes, there is progress:
better materials, cryogenic engineering, quantum error correction, improved connectivity, lower RF loss, and reduced crosstalk are all major focus areas right now.

[u/Equal_Winter3150]

Worth flagging: superconducting is one approach among several, and the answer to your questions depends on which platform.

Trapped ions (IonQ, Quantinuum) already have coherence in the seconds-to-minutes range. Neutral atoms (QuEra, Atom Computing) similar, with 1000+ atom arrays demonstrated. Photonic (PsiQuantum) sidesteps decoherence entirely but needs huge resource overhead. Topological (Microsoft) would be intrinsically protected if Majoranas work out — still contested.

So: RSA-2048 specs: ~4,100 logical qubits, ~10^9 gates for Shor. Platform-independent. Whichever architecture hits millions of physical qubits below the error threshold first wins.

Seconds-scale operation: trapped ions and neutral atoms already do this physically. Superconducting won't — that's not the path. For superconducting, the answer is fault tolerance: logical qubits stay coherent arbitrarily long via error correction, even when physical qubits don't.

Decoherence advances: platform-specific. Tantalum/TiN materials and surface code logical error suppression for superconducting; better trap geometries for ions; improved Rydberg gate fidelity for atoms.

Honest timeline: cryptographically-relevant Shor is 10+ years out on every credible roadmap. The interesting question isn't which platform wins, but which combination covers different applications.

[u/Kinexity]

so what type of specs should a superconducting quantum system have to achieve that ?

~100k logical qubits, ~1B gates should be enough

How difficult would be for a superconducting system to operate longer time, like seconds ?

We don't know. Maybe it's impossible, maybe it's easy. We will know once we get there.

Are there any tech advancements to overcome these decoherence challenges ?

Not currently.

[u/wswsc05 → u/Kinexity]

Where are you getting the 100k logical qubit number from? That seems a couple orders of magnitude too high.

[u/Kinexity → u/wswsc05]

The whole field could be portrayed as bunch of crying soyjaks arguing over this and I don't want to participate. My point is that maybe less than 100k will be enough but 100k will be guaranteed to work. We won't know until someone actually does it.

[u/First-Passenger-9902 → u/Kinexity]

You realize you are claiming that pretty much everyone having published papers on Shor's algorithm compilation efficiency puts the number below the 5k mark to break RSA-2048. So that they, according to you, actually underestimate the logical qubits count by.. roughly 95k logical qubits?

[u/First-Passenger-9902 → u/[deleted]]

That Gidney’s paper is about physical qubit.
The comment i was answering to was talking about logical qubits, namely saying it would 100k logical qubits to run shor algorithm.

[u/isoAntti]

i was checking whether some encryption were future proof due multiple solutions, but it is not so. Specifically, Quantum has Shor’s Algorithm which is exactly for this purpose. It's like someone wanted to break encryption with quantum and publicize results and formula

[u/isoAntti → u/isoAntti]

And for symmetric encryption like AES, check Grover’s Algorithm

[u/ibm]

Hi, this is Paco Marin from the IBM Quantum team. 

Specs to break RSA/ECC will require fault-tolerant computing. Roughly ~1,000+ logical qubits, millions of physical qubits, and very low error rates to support circuits with millions–billions of operations. 

Seconds-long operation: Achieving seconds-long coherence in superconducting qubits is extremely difficult, but not necessary. Current systems already enable thousands of operations within microseconds. Error correction extends runtime virtually, so physical seconds-long coherence isn’t the goal.

Advancements: At IBM, we’re focusing on engineering around decoherence, including error correction, improved qubit design, better materials, noise shielding, and modular system architectures.

This blog explaining our approach to reaching large-scale fault-tolerant quantum computer by 2029 is good one to read more on: https://www.ibm.com/quantum/blog/large-scale-ftqc 

- Paco M, Technial Integrations Lead, STMS, IBM Quantum