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Quantum algorithms for nonlinear differential equations

Given a system of nonlinear ordinary differential equations, in the primary algorithm's case a dissipative quadratic n-dimensional system, produce the solution at a chosen evolution time T to error ε, encoded in the amplitudes of a quantum state.

Attested & literatureUpdated

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  • Record typeLiterature reference
  • Speedup class (secondary source)Superpolynomial
  • Primary source on the speedupNot checked against the primary source yet
  • Reported costFor dissipative quadratic n-dimensional ODEs with R < 1, complexity T² q poly(log T, log n, log 1/ε)/ε, where T is the evolution time, ε the allowed error and q measures decay of the solution; a worst-case lower bound in the same paper shows the general quadratic problem is intractable for R ≥ √2. The earlier Leyton and Osborne algorithm has expected resource requirements polylogarithmic in the number of variables but exponential in the integration time, against a best classical algorithm scaling linearly in the number of variables.
  • Papers2
Record type
Literature reference
Speedup class (secondary source)
Superpolynomial
Primary source on the speedup
Not checked against the primary source yet
Reported cost
For dissipative quadratic n-dimensional ODEs with R < 1, complexity T² q poly(log T, log n, log 1/ε)/ε, where T is the evolution time, ε the allowed error and q measures decay of the solution; a worst-case lower bound in the same paper shows the general quadratic problem is intractable for R ≥ √2. The earlier Leyton and Osborne algorithm has expected resource requirements polylogarithmic in the number of variables but exponential in the integration time, against a best classical algorithm scaling linearly in the number of variables.
Speedup class
Superpolynomial (not yet checked against the record's own primary paper)
Complexity basis
abstract of arXiv:2011.03185: "Assuming R < 1, where R is a parameter characterizing the ratio of the nonlinearity and forcing to the linear dissipation, this algorithm has complexity T^2 q poly(log T, log n, log 1/epsilon)/epsilon, where T is the evolution time, epsilon is the allowed error, and q measures decay of the solution", and "a lower bound on the worst-case complexity of quantum algorithms for general quadratic differential equations, showing that the problem is intractable for R >= sqrt(2)"; second bound from the abstract of arXiv:0812.4423: "its expected resource requirements are polylogarithmic in the number of variables and exponential in the integration time. The best classical algorithm runs in a time scaling linearly with the number of variables."
Circuit
Not supplied

References

  • Efficient quantum algorithm for dissipative nonlinear differential equations

    Jin-Peng Liu, Herman Øie Kolden, Hari K. Krovi, Nuno F. Loureiro, Konstantina Trivisa, Andrew M. Childs · 2020

    The Carleman linearization algorithm the Zoo credits with T² scaling, together with its convergence theorem, its R < 1 condition, and the accompanying intractability bound for R ≥ √2; it also reports that the condition can be met in realistic epidemiological models.

  • A quantum algorithm to solve nonlinear differential equations

    Sarah K. Leyton, Tobias J. Osborne · 2008

    The earlier approach the Zoo describes as exponential in t: a nondeterministic algorithm for sparse nonlinear systems with polynomial nonlinear terms, built from a nonlinear transformation of the amplitudes of an unknown state and a quantum implementation of Euler's method.

Attested & literature
  • Peer-reviewed paper
Method
Curation only. The problem statement was recorded from the literature; the speedup class is not yet checked against the record's own primary paper; the primary reference's title, authors and submission year were read from its arXiv abs page; the complexity claim was taken from a clause of that paper's abstract (abstract of arXiv:2011.03185: "Assuming R < 1, where R is a parameter characterizing the ratio of the nonlinearity and forcing to the linear dissipation, this algorithm has complexity T^2 q poly(log T, log n, log 1/epsilon)/epsilon, where T is the evolution time, epsilon is the allowed error, and q measures decay of the solution", and "a lower bound on the worst-case complexity of quantum algorithms for general quadratic differential equations, showing that the problem is intractable for R >= sqrt(2)"; second bound from the abstract of arXiv:0812.4423: "its expected resource requirements are polylogarithmic in the number of variables and exponential in the integration time. The best classical algorithm runs in a time scaling linearly with the number of variables."). No circuit was constructed, simulated or run.
Result
Pass · the record's problem, speedup class and primary reference agree with the two sources named above.
Caveat
This is a literature record. Nothing was executed for it: no circuit was built, compiled, simulated, or benchmarked, and no resource count is claimed. The T² bound holds only inside the stated regime, a dissipative quadratic system with R < 1, and says nothing about systems outside it; the paper's support for larger R in a fluid-dynamics model is described in its own abstract as numerical evidence, not a proof. Because the solution lives in the amplitudes of a quantum state, unitarity means the approach is inefficient when the solution's norm grows or shrinks too rapidly, and the cost of reading individual solution components back out is not established here, nor are constant factors, the input-access model, or hardware feasibility.
Efficient quantum algorithm for dissipative nonlinear differential equations ↗
Kind
curated reference
Reviewed by
Leona Quantum curation pass
License
Citation metadata only; source publication terms apply
differential equationsnonlinearcarleman linearizationamplitude encoding

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