Experimental quantum simulation of a topologically protected Hadamard gate via braiding Fibonacci anyons.

Topological quantum computation (TQC) is one of the most striking architectures that can realize fault-tolerant quantum computers. In TQC, the logical space and the quantum gates are topologically protected, i.e.

Dynamical-invariant-based holonomic quantum gates: Theory and experiment.

Among existing approaches to holonomic quantum computing, the adiabatic holonomic quantum gates (HQGs) suffer errors due to decoherence, while the non-adiabatic HQGs either require additional Hilbert spaces or are difficult to scale. Here, we report a systematic, scalable approach based on dynamical invariants to realize HQGs without using additional Hilbert spaces. While presenting the theoretical framework of our approach, we design and experimentally evaluate single-qubit and two-qubits HQGs for the nuclear magnetic resonance system.

Experimental Identification of Non-Abelian Topological Orders on a Quantum Simulator.

Topological orders can be used as media for topological quantum computing-a promising quantum computation model due to its invulnerability against local errors. Conversely, a quantum simulator, often regarded as a quantum computing device for special purposes, also offers a way of characterizing topological orders. Here, we show how to identify distinct topological orders via measuring their modular S and T matrices.

Ground-state degeneracy of topological phases on open surfaces.

We relate the ground state degeneracy of a non-Abelian topological phase on a surface with boundaries to the anyon condensates that break the topological phase into a trivial phase. Specifically, we propose that gapped boundary conditions of the surface are in one-to-one correspondence with the sets of condensates, each being able to completely break the phase, and we substantiate this by examples. The ground state degeneracy resulting from a particular boundary condition coincides with the number of confined topological sectors due to the corresponding condensation.

Subpeaks in the Brillouin loss spectra of distributed fiber-optic sensors.

Subpeaks in the Brillouin loss spectra of distributed fiber-optic sensors were observed for what is believed to be the first time and studied. We discovered that the Fourier spectrum of the pulsed signal and the off-resonance oscillation both contributed to subpeaks. The off-resonance oscillation at frequency /v - vB/ is the oscillation in the Brillouin time domain when beat frequency v of the two counterpropagating laser beams does not match local Brillouin frequency vB.

Effect of optical phase on a distributed Brillouin sensor at centimeter spatial resolution.

Because of the power imbalance between the two arms of an interferometer in an electro-optic modulator (EOM), the output of the EOM is combined amplitude modulation (AM) and phase modulation (PM) for the probe signal consisting of the pulse and the dc component. Because of this PM, the Brillouin gain-loss spectrum becomes asymmetric. The central Brillouin frequency is shifted from that of an AM pulse.

Coherent probe-pump-based Brillouin sensor for centimeter-crack detection.

We provide a theoretical explanation for a coherent probe-pump-based Brillouin sensor system that achieves centimeter spatial resolution with high-frequency resolution. It was recently discovered that, when a combination of cw and pulsed light (the probe beam) interacts with a cw laser (the pump beam), centimeter spatial resolution with high-frequency resolution can be achieved even though the probe-pulse duration is 1.5 ns [Opt.