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> Can anyone expound further on the practical applications of quantum computing? My research is in molecular dynamics simulations and quantum chemistry. A lot

> Can anyone expound further on the practical applications of quantum computing? My research is in molecular dynamics simulations and quantum chemistry. A lot of progress has been made in the field in the last few decades; however, there is a roadblock right now that no one really knows how to get around called the fermion sign problem. If we want to simulate atoms or molecules as accurately as we can, the number of resources we require scales exponentially with the number of particles. This is basically due to the Coulombic (electrostatic) interactions between the electrons in the atom. Accounting for these interactions gives many materials their interesting properties, but we've only been able to come up with approximations for solving these systems. Quantum computing would allow these systems to be solved in polynomial time. The advantage would be enormous; in some cases, atomic simulation results would match experimental ones exactly†, and that is a very exciting notion. (†glossing over a huge number of details here)

nhstanley 12y ago
It seems clear that quantum computing would help with QM calculations (which I think you were mainly talking about), but it is less clear to me if it would help with things like MD (and perhaps it wouldn't matter if QM could be sped up enough). Could quantum computing help with MD or other kinds of simulations (e.g. monte carlo) where we are essentially searching for a minima? I have heard that quantum annealing, which some argue the first QC system are really doing, would work on this. But it's all too confusing. It seems like half of what I read about quantum computing would say "Yes!" to that, and half is saying "you don't understand".
- Xcelerate 12y ago
  It could help with MD. A lot of MD potentials are developed by kind of regressing results from QM calculations for different atomic configurations (e.g. some versions of ReaxFF are based off of DFT calculations). I actually don't know a whole lot about how exactly QC speeds up computations for things like Quantum Monte Carlo, I just know that an algorithm exists for it (much like Shor's algorithm speeds up integer factorization, but the details are murky for me). I'll have to see if I can find which paper that is.
  - mathgenius 12y ago
    Check this out: http://arxiv.org/abs/1406.4920 http://arxiv.org/abs/1406.4920

nhstanley 12y ago

It seems clear that quantum computing would help with QM calculations (which I think you were mainly talking about), but it is less clear to me if it would help with things like MD (and perhaps it wouldn't matter if QM could be sped up enough). Could quantum computing help with MD or other kinds of simulations (e.g. monte carlo) where we are essentially searching for a minima? I have heard that quantum annealing, which some argue the first QC system are really doing, would work on this. But it's all too confusing. It seems like half of what I read about quantum computing would say "Yes!" to that, and half is saying "you don't understand".

Xcelerate 12y ago
It could help with MD. A lot of MD potentials are developed by kind of regressing results from QM calculations for different atomic configurations (e.g. some versions of ReaxFF are based off of DFT calculations). I actually don't know a whole lot about how exactly QC speeds up computations for things like Quantum Monte Carlo, I just know that an algorithm exists for it (much like Shor's algorithm speeds up integer factorization, but the details are murky for me). I'll have to see if I can find which paper that is.
- mathgenius 12y ago
  Check this out: http://arxiv.org/abs/1406.4920 http://arxiv.org/abs/1406.4920