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Electronic Colloquium on Computational Complexity

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Reports tagged with quantum complexity:
TR99-003 | 18th December 1998
Stephen A. Fenner, Frederic Green, Steven Homer, Randall Pruim

Determining Acceptance Possibility for a Quantum Computation is Hard for the Polynomial Hierarchy

It is shown that determining whether a quantum computation
has a non-zero probability of accepting is at least as hard as the
polynomial time hierarchy. This hardness result also applies to
determining in general whether a given quantum basis state appears
with nonzero amplitude in a superposition, or whether a ... more >>>

TR02-013 | 30th January 2002
Chris Pollett, Farid Ablayev, Cristopher Moore, Chris Pollett

Quantum and Stochastic Programs of Bounded Width

Revisions: 1

We prove upper and lower bounds on the power of quantum and stochastic
branching programs of bounded width. We show any NC^1 language can
be accepted exactly by a width-2 quantum branching program of
polynomial length, in contrast to the classical case where width 5 is
necessary unless \NC^1=\ACC. ... more >>>

TR04-120 | 22nd November 2004
Andris Ambainis, William Gasarch, Aravind Srinivasan, Andrey Utis

Lower bounds on the Deterministic and Quantum Communication Complexity of HAM_n^a

Alice and Bob want to know if two strings of length $n$ are
almost equal. That is, do they differ on at most $a$ bits?
Let $0\le a\le n-1$.
We show that any deterministic protocol, as well as any
error-free quantum protocol ($C^*$ version), for this problem
requires at ... more >>>

TR08-085 | 19th June 2008
Farid Ablayev, Airat Khasianov, Alexander Vasiliev

On Complexity of Quantum Branching Programs Computing Equality-like Boolean Functions

Revisions: 1

We consider Generalized Equality, the Hidden Subgroup,
and related problems in the context of quantum Ordered Binary
Decision Diagrams. For the decision versions of considered problems
we show polynomial upper bounds in terms of quantum OBDD width. We
apply a new modification of the fingerprinting technique and present
the algorithms ... more >>>

TR10-030 | 18th February 2010
Airat Khasianov

Stronger Lower Bounds on Quantum OBDD for the Hidden Subgroup Problem

Revisions: 2

We consider the \emph{Hidden Subgroup} in the context of quantum \emph{Ordered Binary Decision Diagrams}.
We show several lower bounds for this function.
In this paper we also consider a slightly more general definition of the
hidden subgroup problem (in contrast to that in \cite{khashsp1}). It turns out that ... more >>>

TR15-108 | 30th June 2015
Shalev Ben-David

A Super-Grover Separation Between Randomized and Quantum Query Complexities

We construct a total Boolean function $f$ satisfying
$R(f)=\tilde{\Omega}(Q(f)^{5/2})$, refuting the long-standing
conjecture that $R(f)=O(Q(f)^2)$ for all total Boolean functions.
Assuming a conjecture of Aaronson and Ambainis about optimal quantum speedups for partial functions,
we improve this to $R(f)=\tilde{\Omega}(Q(f)^3)$.
Our construction is motivated by the Göös-Pitassi-Watson function
but does not ... more >>>

ISSN 1433-8092 | Imprint