Quantum simulation of cosmic inflation

AbstractSimulating the behaviour of complex quantum systems is impossible on classical supercomputers due to the exponential scaling of the number of quantum states with the number of particles in the simulated system. Quantum computers aim to break through this limit by using one quantum system to simulate another quantum system. Although in their infancy, they are a promising tool for applied fields seeking to simulate quantum interactions in complex atomic and molecular structures. Here, we show an efficient technique for transpiling the unitary evolution of quantum systems into the language of universal quantum computation using the IBM quantum computer and show that it is a viable tool for compiling near-term quantum simulation algorithms. We develop code that decomposes arbitrary 3-qubit gates and implement it in a quantum simulation first for a linear ordered chain to highlight the generality of the approach, and second, for a complex molecule. We choose the Fenna-Matthews-Olsen (FMO) photosynthetic protein because it has a well characterised Hamiltonian and presents a complex dissipative system coupled to a noisy environment that helps to improve the efficiency of energy transport. The method can be implemented in a broad range of molecular and other simulation settings.

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Duality quantum simulation of a generalized anti-PT-symmetric two-level system

EPL (Europhysics Letters) ◽

10.1209/0295-5075/126/30005 ◽

2019 ◽

Vol 126 (3) ◽

pp. 30005 ◽

Cited By ~ 3

Author(s):

Chao Zheng

Keyword(s):

Quantum Simulation ◽

Level System

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SMOOTHED QUANTUM FLUCTUATIONS AND CMB OBSERVATIONS

International Journal of Modern Physics D ◽

10.1142/s0218271812500800 ◽

2012 ◽

Vol 21 (10) ◽

pp. 1250080

Author(s):

JAKUB MIELCZAREK ◽

MICHAŁ KAMIONKA

Keyword(s):

Scalar Field ◽

Power Spectrum ◽

Internal Structure ◽

Planck Scale ◽

Quantum Fluctuations ◽

Gaussian Smoothing ◽

Cosmic Inflation ◽

Smoothing Factor ◽

High Multipoles

In this paper, we investigate power spectrum of a smoothed scalar field. The smoothing leads to regularization of the UV divergences and can be related with the internal structure of the considered field or the space itself. We perform Gaussian smoothing to the quantum fluctuations generated during the phase of cosmic inflation. We study whether this effect can be probed observationally and conclude that the modifications of the power spectrum due to the smoothing on the Planck scale are negligible and far beyond the observational abilities. Subsequently, we investigate whether smoothing in any other form can be probed observationally. We introduce phenomenological smoothing factor e-k2σ2 to the inflationary spectrum and investigate its effects on the spectrum of CMB anisotropies and polarization. We show that smoothing can lead to suppression of high multipoles in the spectrum of the CMB. Based on seven years observations of WMAP satellite we indicate that the present scale of high multipoles suppression is constrained by σ < 3.19 Mpc (95% CL). This corresponds to the constraint σ < 100 μm at the end of inflation. Despite this value is far above the Planck scale, other processes of smoothing can be possibly studied with this constraint, as decoherence or diffusion of primordial perturbations.

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