scholarly journals Adversary lower bounds for the collision and the set equality problems

2018 ◽  
Vol 18 (3&4) ◽  
pp. 198-222
Author(s):  
Aleksandrs Belovs ◽  
Ansis Rosmanis
Keyword(s):  
Lower Bounds ◽  
Query Complexity ◽  
Negative Weight ◽  
Quantum Query Complexity ◽  
Adversary Method ◽  
Quantum Query

We prove tight \Omega(n^{1/3}) lower bounds on the quantum query complexity of the Collision and the Set Equality problems, provided that the size of the alphabet is large enough. We do this using the negative-weight adversary method. Thus, we reprove the result by Aaronson and Shi, as well as a more recent development by Zhandry.

scholarly journals Explicit relation between all lower bound techniques for quantum query complexity

2015 ◽  
Vol 13 (04) ◽  
pp. 1350059
Author(s):  
Loïck Magnin ◽  
Jérémie Roland
Keyword(s):  
Lower Bound ◽  
Boolean Functions ◽  
Query Complexity ◽  
Polynomial Method ◽  
Quantum Query Complexity ◽  
State Generation ◽  
Adversary Method ◽  
Explicit Relation ◽  
Special Case ◽  
Quantum Query

The polynomial method and the adversary method are the two main techniques to prove lower bounds on quantum query complexity, and they have so far been considered as unrelated approaches. Here, we show an explicit reduction from the polynomial method to the multiplicative adversary method. The proof goes by extending the polynomial method from Boolean functions to quantum state generation problems. In the process, the bound is even strengthened. We then show that this extended polynomial method is a special case of the multiplicative adversary method with an adversary matrix that is independent of the function. This new result therefore provides insight on the reason why in some cases the adversary method is stronger than the polynomial method. It also reveals a clear picture of the relation between the different lower bound techniques, as it implies that all known techniques reduce to the multiplicative adversary method.

Quantum collision-resistance of non-uniformly distributed functions: upper and lower bounds

2018 ◽  
Vol 18 (15&16) ◽  
pp. 1332-1349
Author(s):  
Ehsan Ebrahimi ◽  
Dominique Unruh
Keyword(s):  
Lower Bound ◽  
Uniform Distribution ◽  
Lower Bounds ◽  
Upper Bounds ◽  
Query Complexity ◽  
Upper And Lower Bounds ◽  
Collision Resistance ◽  
Quantum Query Complexity ◽  
Quantum Query

We study the quantum query complexity of finding a collision for a function f whose outputs are chosen according to a non-uniform distribution D. We derive some upper bounds and lower bounds depending on the min-entropy and the collision-entropy of D. In particular, we improve the previous lower bound by Ebrahimi Targhi et al. from \Omega(2^{k/9}) to \Omega(2^{k/5}) where k is the min-entropy of D.

scholarly journals The quantum query complexity of certification

2010 ◽  
Vol 10 (3&4) ◽  
pp. 181-189
Author(s):  
A. Ambainis ◽  
A.M. Childs ◽  
F. Le Gall ◽  
S. Tani
Keyword(s):  
Lower Bound ◽  
Query Complexity ◽  
Direct Sum ◽  
Quantum Query Complexity ◽  
Sum Theorem ◽  
Adversary Method ◽  
Quantum Query

We study the quantum query complexity of finding a certificate for a d-regular, k-level balanced \nand formula. We show that the query complexity is $\tilde\Theta(d^{(k+1)/2})$ for 0-certificates, and $\tilde\Theta(d^{k/2})$ for 1-certificates. In particular, this shows that the zero-error quantum query complexity of evaluating such formulas is $\tilde O(d^{(k+1)/2})$. Our lower bound relies on the fact that the quantum adversary method obeys a direct sum theorem.

scholarly journals Exact quantum algorithms have advantage for almost all Boolean functions

2015 ◽  
pp. 435-452
Author(s):  
Andris Ambainis ◽  
Jozef Gruska ◽  
Shenggen Zheng
Keyword(s):  
Boolean Function ◽  
Boolean Functions ◽  
Quantum Algorithms ◽  
Quantum Algorithm ◽  
Query Complexity ◽  
Exact Quantum ◽  
Quantum Query Complexity ◽  
Almost All ◽  
Quantum Query

It has been proved that almost all n-bit Boolean functions have exact classical query complexity n. However, the situation seemed to be very different when we deal with exact quantum query complexity. In this paper, we prove that almost all n-bit Boolean functions can be computed by an exact quantum algorithm with less than n queries. More exactly, we prove that ANDn is the only n-bit Boolean function, up to isomorphism, that requires n queries.

Open Problems Related to Quantum Query Complexity

2021 ◽  
Vol 2 (4) ◽  
pp. 1-9
Author(s):  
Scott Aaronson
Keyword(s):  
Synthesis Problem ◽  
Query Complexity ◽  
Partial Functions ◽  
Open Problems ◽  
Polynomial Degree ◽  
Quantum Query Complexity ◽  
Time Space ◽  
Quantum Query

I offer a case that quantum query complexity still has loads of enticing and fundamental open problems—from relativized QMA versus QCMA and BQP versus IP , to time/space tradeoffs for collision and element distinctness, to polynomial degree versus quantum query complexity for partial functions, to the Unitary Synthesis Problem and more.

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