blog/2021/11/quantum-computing-for-quantum-chemistry-a-brief-perspective/

[utterances-bot]

Quantum computing for quantum chemistry: a brief perspective | PennyLane Blog

We share two short lessons regarding the leading quantum algorithms for quantum chemistry: the variational quantum eigensolver and quantum phase estimation.

https://pennylane.ai/blog/2021/11/quantum-computing-for-quantum-chemistry-a-brief-perspective/

[zengjk]

That being said the complexity of VQE scales with the number of qubit in a polynomial way which is obviously far better than exponential grow as the dimension of Hilbert space does, so VQE is still promising at large?

[Danimhn]

Hey Junkai, Danial from the algorithms team here :)

To give you some context, for some practical problems of interest, you could need approximately 10^20 measurements just to evaluate the objective function once within chemical accuracy. And remember, that's just for a single function evaluation, and not the optimization problem itself which comes with its own unique challenges. These include barren plateaus, inefficiencies in gradient computations on a quantum computer, and the QMA-completeness of the general task of ground state preparation. So theoretically, the general problem is exponentially hard even on a quantum computer.