Abstract
The efficient simulation of quantum systems is a primary motivating factor for developing controllable quantum machines. For addressing systems with underlying bosonic structure, it is advantageous to utilize a naturally bosonic platform. Optical photons passing through linear networks may be configured to perform quantum simulation tasks, but the efficient preparation and detection of multiphoton quantum states of light in linear optical systems are challenging. Here, we experimentally implement a boson sampling protocol for simulating molecular vibronic spectra [J. Huh et al., Nat. Photonics 9, 615 (2015)] in a two-mode superconducting device. In addition to enacting the requisite set of Gaussian operations across both modes, we fulfill the scalability requirement by demonstrating, for the first time in any platform, a high-fidelity single-shot photon number resolving detection scheme capable of resolving up to 15 photons per mode. Furthermore, we exercise the capability of synthesizing non-Gaussian input states to simulate spectra of molecular ensembles in vibrational excited states. We show the reprogrammability of our implementation by extracting the spectra of photoelectron processes in , , , and . The capabilities highlighted in this work establish the superconducting architecture as a promising platform for bosonic simulations, and by combining them with tools such as Kerr interactions and engineered dissipation, enable the simulation of a wider class of bosonic systems.
2 More- Received 16 December 2019
- Revised 30 March 2020
- Accepted 27 April 2020
DOI:https://doi.org/10.1103/PhysRevX.10.021060
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Sampling Photons to Simulate Molecules
Published 17 June 2020
A quantum simulator uses microwave photons to tackle a useful chemistry problem—determining the vibronic spectra of molecules.
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Popular Summary
Natural systems are composed of elementary particles that are either bosons or fermions. Simulating these systems on a large scale at the quantum-mechanical level is a primary motivation for developing quantum simulators. However, conventionally envisioned quantum computers manipulate qubits that lack the quantum statistics of bosons or fermions. This necessitates a mapping cost between bosons or fermions and qubit spins, which incurs significant overhead. Thus, it is desirable to develop quantum simulators that obviate this overhead by exploiting the natural statistics of the hardware. To that end, we have developed a fully controllable bosonic simulator and used it to perform the first scalable simulation of molecular vibronic spectra.
Our approach identifies a one-to-one correspondence between photonic cavity modes and molecular vibrational modes. We develop a bosonic simulator that integrates superconducting microwave cavities with nonlinear Josephson circuits. The nonlinear elements enable arbitrary state preparation, a complete set of operations, and detection of single photons. With these capabilities, we transform the photonic state of the processor to mimic how a molecular vibrational state would reconfigure as a result of an electronic transition. Using a novel photon-number-resolving detector, we directly sample from the output state and extract the relative intensities of the molecule’s corresponding electronic absorption spectrum. We demonstrate programmability by simulating photoelectron spectra in water, ozone, nitrite, and sulfur dioxide.
Our work serves as a basis for superconducting bosonic quantum simulation. By adding further nonlinear control, our platform could simulate a wider range of bosonic systems.