Synopsis: Simulating a molecule

An NMR-based quantum computer can simulate a hydrogen molecule and accurately yield its ground-state energy.
Synopsis figure
Illustration: J. Du et al., Phys. Rev. Lett (2010)

In the early 1980s, Richard Feynman proposed using a computer that followed the rules of quantum mechanics to mimic a physical system—not in the way digital computers perform numerical simulations, but something closer in spirit to an analog computer where expectation values of some quantum subunit were the “readout.”

Today, we know these devices as quantum computers and intense efforts are focused on scaling them up to make useful computational devices. But investigations into Feynman’s original notion of quantum computers as “quantum simulators” still exist. Several groups have reported results with quantum computers based on nuclear magnetic resonance (NMR) and ion-trap methods, including molecular simulators that calculate molecular energy levels.

Writing in Physical Review Letters, Jiangfeng Du and colleagues at the Hefei National Lab for Physical Sciences at the Microscale in China report their work on using a quantum computer to simulate a hydrogen molecule. The simulation is performed with NMR-based quantum information processing: isotopically labeled chloroform molecules act as the processing medium, with 13C serving as the system qubit. By applying a sequence of NMR pulses to the chloroform, Du et al. can prepare an initial state of the carbon, manipulate the qubits in a controlled way, and read out the qubit phase shifts to generate a value for the ground-state energy of a hydrogen molecule. Although only a proof-of-principle on a test case, Du et al. are able to carry out the computation with 45-bit precision and show the potential for quantum information processing in quantum chemistry calculations. – David Voss


Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsQuantum Information

Previous Synopsis

Atomic and Molecular Physics

Opening the gate to quantum computation

Read More »

Next Synopsis

Related Articles

Viewpoint: Unlocking the Hidden Information in Starlight
Astrophysics

Viewpoint: Unlocking the Hidden Information in Starlight

Quantum metrology shows that it is always possible to estimate the separation of two stars, no matter how close together they are. Read More »

Viewpoint: Ionization Delays That Stand Out
Optics

Viewpoint: Ionization Delays That Stand Out

Attosecond-resolution experiments have determined the delay in an electron’s emission from a molecule after being ionized with light. Read More »

Focus: Giant Molecule Made from Two Atoms
Atomic and Molecular Physics

Focus: Giant Molecule Made from Two Atoms

Experiments confirm the existence of 1-micrometer-sized molecules made of two cesium atoms by showing that their binding energies agree with predictions.   Read More »

More Articles