Quantum Catalytic Space

Fuente: arXiv
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Autori principali: Buhrman, Harry, Folkertsma, Marten, Mertz, Ian, Speelman, Florian, Strelchuk, Sergii, Subramanian, Sathyawageeswar, Tupker, Quinten
Natura: Preprint
Pubblicazione: 2025
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author Buhrman, Harry
Folkertsma, Marten
Mertz, Ian
Speelman, Florian
Strelchuk, Sergii
Subramanian, Sathyawageeswar
Tupker, Quinten
author_facet Buhrman, Harry
Folkertsma, Marten
Mertz, Ian
Speelman, Florian
Strelchuk, Sergii
Subramanian, Sathyawageeswar
Tupker, Quinten
contents Space complexity is a key field of study in theoretical computer science. In the quantum setting there are clear motivations to understand the power of space-restricted computation, as qubits are an especially precious and limited resource. Recently, a new branch of space-bounded complexity called catalytic computing has shown that reusing space is a very powerful computational resource, especially for subroutines that incur little to no space overhead. While quantum catalysis in an information theoretic context, and the power of ``dirty'' qubits for quantum computation, has been studied over the years, these models are generally not suitable for use in quantum space-bounded algorithms, as they either rely on specific catalytic states or destroy the memory being borrowed. We define the notion of catalytic computing in the quantum setting and show a number of initial results about the model. First, we show that quantum catalytic logspace can always be computed quantumly in polynomial time; the classical analogue of this is the largest open question in catalytic computing. This also allows quantum catalytic space to be defined in an equivalent way with respect to circuits instead of Turing machines. We also prove that quantum catalytic logspace can simulate log-depth threshold circuits, a class which is known to contain (and believed to strictly contain) quantum logspace, thus showcasing the power of quantum catalytic space. Finally we show that both unitary quantum catalytic logspace and classical catalytic logspace can be simulated in the one-clean qubit model.
format Preprint
id arxiv_https___arxiv_org_abs_2506_16324
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Catalytic Space
Buhrman, Harry
Folkertsma, Marten
Mertz, Ian
Speelman, Florian
Strelchuk, Sergii
Subramanian, Sathyawageeswar
Tupker, Quinten
Quantum Physics
Space complexity is a key field of study in theoretical computer science. In the quantum setting there are clear motivations to understand the power of space-restricted computation, as qubits are an especially precious and limited resource. Recently, a new branch of space-bounded complexity called catalytic computing has shown that reusing space is a very powerful computational resource, especially for subroutines that incur little to no space overhead. While quantum catalysis in an information theoretic context, and the power of ``dirty'' qubits for quantum computation, has been studied over the years, these models are generally not suitable for use in quantum space-bounded algorithms, as they either rely on specific catalytic states or destroy the memory being borrowed. We define the notion of catalytic computing in the quantum setting and show a number of initial results about the model. First, we show that quantum catalytic logspace can always be computed quantumly in polynomial time; the classical analogue of this is the largest open question in catalytic computing. This also allows quantum catalytic space to be defined in an equivalent way with respect to circuits instead of Turing machines. We also prove that quantum catalytic logspace can simulate log-depth threshold circuits, a class which is known to contain (and believed to strictly contain) quantum logspace, thus showcasing the power of quantum catalytic space. Finally we show that both unitary quantum catalytic logspace and classical catalytic logspace can be simulated in the one-clean qubit model.
title Quantum Catalytic Space
topic Quantum Physics
url https://arxiv.org/abs/2506.16324