Abstract
Quantum computing technologies promise to revolutionize calculations in many areas of physics, chemistry, and data science. Their power is expected to be especially pronounced for problems where direct analogs of a quantum system under study can be encoded coherently within a quantum computer. A first step toward harnessing this power is to express the building blocks of known physical systems within the language of quantum gates and circuits. In this paper, we present a quantum calculation of an archetypal quantum system: neutrino oscillations. We define gate arrangements that implement the neutral lepton mixing operation and neutrino time evolution in two-, three-, and four-flavor systems. We then calculate oscillation probabilities by coherently preparing quantum states within the processor, time evolving them unitarily, and performing measurements in the flavor basis, with close analogy to the physical processes realized in neutrino oscillation experiments, finding excellent agreement with classical calculations. We provide recipes for modeling oscillation in the standard three-flavor paradigm as well as beyond-standard-model scenarios, including systems with sterile neutrinos, non-standard interactions, Lorentz symmetry violation, and anomalous decoherence.
Highlights
The unexpected and Nobel Prize–winning discovery of neutrino oscillations [1] has led to a program of experiment and theory that has shaped the understanding of the role of neutrinos in the Universe
After testing that our quantum circuit reproduces the quantum neutrino oscillation probability on the IBM Q public quantum computer, we conclude with a brief discussion of how to include more complex phenomena including sterile neutrinos, matter effects, nonstandard interactions, Lorentz symmetry violation, and decoherence within the quantum algorithm
The quantum evolution matches very well with expectations from both theory and quantum simulation. For this circuit and others described in this paper we have chosen gate arrangements that are simple and intuitive, mirroring the quantum operations involved in physical neutrino oscillations
Summary
The unexpected and Nobel Prize–winning discovery of neutrino oscillations [1] has led to a program of experiment and theory that has shaped the understanding of the role of neutrinos in the Universe. The spontaneous transition of neutrino flavor over macroscopic distances, a phenomenon known as neutrino oscillations due to its periodic behavior, demonstrates that neutrinos have masses that are nonzero but uniquely small This smallness suggests connections to highscale physics [2,3,4] and may be related directly to the predominance of matter over antimatter abundances in the Universe [5]. This work demonstrates the processing of three-neutrino flavor information in a quantum simulation, executing an analogous Hamiltonian evolution to generate neutrino flavor oscillations. Systems that could benefit from a quantum algorithmic approach to neutrino flavor evolution include those where collective neutrino oscillations [38,39] are relevant, such as in supernovae or the early Universe [40]. After testing that our quantum circuit reproduces the quantum neutrino oscillation probability on the IBM Q public quantum computer, we conclude with a brief discussion of how to include more complex phenomena including sterile neutrinos, matter effects, nonstandard interactions, Lorentz symmetry violation, and decoherence within the quantum algorithm
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