Paul Anthony Benioff (May 1, 1930 – March 29, 2022) was an American physicist who helped pioneer the field of quantum computing. Benioff was best known for his research in quantum information theory during the 1970s and 80s that demonstrated the theoretical possibility of quantum computers by describing the first quantum mechanical model of a computer. In this work, Benioff showed that a computer could operate under the laws of quantum mechanics by describing a Schrödinger equation description of Turing machines. Benioff's body of work in quantum information theory encompassed quantum computers, quantum robots, and the relationship between foundations in logic, math, and physics.

Benioff was born on May 1, 1930, in Pasadena, California. His father, Hugo Benioff, was a professor of seismology at the California Institute of Technology, and his mother, Alice Pauline Silverman, received a master's degree in English from the University of California, Berkeley.

Benioff also attended Berkeley, where he earned an undergraduate degree in botany in 1951. After a two-year stint working in nuclear chemistry for Tracerlab, he returned to Berkeley. In 1959, he obtained his PhD in nuclear chemistry.

In 1960, Benioff spent a year at the Weizmann Institute of Science in Israel as a postdoctoral fellow. He then spent six months at the Niels Bohr Institute in Copenhagen as a Ford Fellow. In 1961, he began a long career at Argonne National Laboratory, first with its Chemistry Division and later in 1978 in the lab's Environmental Impact Division. Benioff remained at Argonne until he retired in 1995. He continued to conduct research at the laboratory as a post-retirement emeritus scientist for the Physics Division until his death in 2022, survived by his wife of 62 years, Hanna (née Hannelore Leshner) and their three children. Chicago Tribune, April 3, 2022.

In addition, Benioff taught the foundations of quantum mechanics as a visiting professor at Tel Aviv University in 1979, and he worked as a visiting scientist at CNRS Marseilles in 1979 and 1982.

In the 1970s, Benioff began to research the theoretical feasibility of quantum computing. His early research culminated in a paper, published in 1980, that described a quantum mechanical model of Turing machines. This work was based on a classical description in 1973 of reversible Turing machines by physicist Charles H. Bennett.

Benioff's model of a quantum computer was reversible and did not dissipate energy. At the time, there were several papers arguing that the creation of a reversible model of quantum computing was impossible. Benioff's paper was the first to show that reversible quantum computing was theoretically possible, which in turn showed the possibility of quantum computing in general. This work, along with later work by several other authors (including David Deutsch, Richard Feynman, and Peter Shor), initiated the field of quantum computing.

In a paper published in 1982, Benioff further developed his original model of quantum mechanical Turing machines. This work put quantum computers on a solid theoretical foundation. Richard Feynman then produced a universal quantum simulator. Building on the work of Benioff and Feynman, Deutsch proposed that quantum mechanics can be used to solve computational problems faster than classical computers, and in 1994, Shor described a factoring algorithm that is considered to have an exponential speedup over classical computers.