Overlapping qubits

Rui Chao, Ben W Reichardt, Chris Sutherland, Thomas Vidick

Research output: Chapter in Book/Report/Conference proceedingConference contribution


An ideal system of n qubits has 2^n dimensions. This exponential grants power, but also hinders characterizing the system's state and dynamics. We study a new problem: the qubits in a physical system might not be independent. They can "overlap," in the sense that an operation on one qubit slightly affects the others. We show that allowing for slight overlaps, n qubits can fit in just polynomially many dimensions. (Defined in a natural way, all pairwise overlaps can be <= epsilon in n^{O(1/epsilon^2)} dimensions.) Thus, even before considering issues like noise, a real system of n qubits might inherently lack any potential for exponential power. On the other hand, we also provide an efficient test to certify exponential dimensionality. Unfortunately, the test is sensitive to noise. It is important to devise more robust tests on the arrangements of qubits in quantum devices.<br />
Original languageEnglish
Title of host publication8th Innovations in Theoretical Computer Science Conference (ITCS 2017)
Number of pages21
StatePublished - 28 Nov 2017
Externally publishedYes
Event8th Innovations in Theoretical Computer Science Conference (ITCS 2017) - Berkeley, CA, USA
Duration: 9 Jan 201711 Jan 2017

Publication series

NameLeibniz International Proceedings in Informatics, LIPIcs
ISSN (Print)1868-8969


Conference8th Innovations in Theoretical Computer Science Conference (ITCS 2017)


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