The Deutsch-Jozsa algorithm is a quantum algorithm, proposed by David Deutsch and Richard Jozsa in It was one of first examples of a. Ideas for quantum algorithm. ▫ Quantum parallelism. ▫ Deutsch-Jozsa algorithm. ▫ Deutsch’s problem. ▫ Implementation of DJ algrorithm. The Deutsch-Jozsa algorithm can determine whether a function mapping all bitstrings to a single bit is constant or balanced, provided that it is one of the two.

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We apply a Hadamard transform to each qubit to obtain. This algorithm is still referred to as Deutsch—Jozsa algorithm in honour of the groundbreaking techniques they employed.

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Constant means all inputs map to the same value, balanced means half of the inputs maps to one value, and half to the other. Quantum circuit Quantum logic gate One-way quantum computer cluster state Adiabatic quantum computation Topological quantum computer. Archived from the original on Views Read Edit View history.

Specifically we were given a boolean function whose input is 1 bit, f: It was one of the first known quantum algorithms that showed an exponential speedup, albeit against a deterministic non-probabilistic classical compuetwr, and with access to a blackbox function that can evaluate inputs to the chosen function.

This page was last edited on 10 Decemberat Read the Docs v: Further improvements to the Deutsch—Jozsa algorithm were made by Cleve et al. It is also a deterministic algorithmmeaning that it always produces an answer, and that answer is always correct.

Rapid solutions of problems by quantum computation. At this point the last qubit may be ignored. First, do Hadamard transformations on n 0s, forming all possible inputs, and a single 1, which will be the answer qubit. For a conventional deterministic algorithm, 2n-1 evaluations of f will be required in the worst case. It preceded other quantum algorithms such as Shor’s algorithm and Grover’s algorithm.


[] An elementary derivation of the Deutsch-Jozsa algorithm

Quantum computing Qubit physical vs. We know that the function in the black box is either constant 0 on all inputs or 1 on all inputs or balanced returns 1 for half the domain and 0 for the other half. Unlike any deterministic classical algorithm, the Deutsch-Jozsa Algorithm can solve this problem jozaa a single iteration, regardless of the input size. Testing these two possibilities, we see the above state is equal to.

Since the problem is easy to solve on a probabilistic classical computer, it does not yield an oracle separation with BPPthe class of problems that can be solved with bounded error in polynomial time on a probabilistic classical computer.

The Deutsch—Jozsa Algorithm generalizes earlier work by David Deutsch, which provided a solution for the simple case. This matrix is exponentially large, and thus even generating the program will take exponential time.

Deutsch-Jozsa algorithm

The motivation is to show a black box problem that can be solved efficiently by a quantum computer with no error, whereas a deterministic classical computer would need a large number of queries to the black box to solve the problem. The Deutsch-Jozsa quantum algorithm produces an answer that is always correct with just 1 evaluation of f.

The Deutsch-Jozsa algorithm can determine whether a function mapping all bitstrings to a single bit is constant or balanced, provided that it is one of the two.

Some but not all of these transformations involve a scratch qubit, so room for one is always provided.


The Deutsch—Jozsa problem is specifically designed to be easy for a quantum algorithm and hard for any deterministic classical algorithm.

If it is 0, the function is constant, otherwise the function is balanced. Proceedings of the Royal Society of London A. From Wikipedia, the free encyclopedia.

Deutsch–Jozsa algorithm

The best case occurs where the function is balanced and the first two output values that happen to be selected are different. In Deutsch-Jozsa problem, we are given a black box computing a valued function f x1, x2, Trapped ion quantum computer Optical lattice. Nielsen and Isaac L.

Retrieved from ” https: This is partially based on the public domain information found here: A constant function always maps to either 1 or algogithm, and a balanced function maps to 1 for half of the inputs and maps to deutach for the other half.

For a conventional randomized algorithma constant number of evaluation suffices to produce the correct answer with a high probability but 2n-1 evaluations are still required if we want an answer that is always correct.

Chuang, “Quantum Computation and Quantum Information”, pages It was one of first examples of a quantum algorithm, which is a class of algorithms designed for execution on Quantum computers and have the potential to be more efficient than conventional, classical, algorithms by taking advantage of the quantum superposition and entanglement principles.

A Hadamard transform is applied to each bit to obtain the state. The algorithm is as follows.