Guanru Feng

Experimental simulation of anyonic fractional statistics with an NMR quantum-information processor

Anyons have exotic statistical properties, fractional statistics, differing from Bosons and Fermions. They can be created as excitations of some Hamiltonian models. Here we present an experimental demonstration of anyonic fractional statistics by simulating a version of the Kitaev spin lattice model proposed by Han et al[Phys. Rev.Lett. 98, 150404 (2007)] using an NMR quantum information processor. We use a 7-qubit system to prepare a 6-qubit pseudopure state to implement the ground state preparation and realize anyonic manipulations, including creation, braiding and anyon fusion. A

Enhancing quantum control by bootstrapping a quantum processor of 12 qubits

\pi/2\times 2

Hyperfine spin qubits in irradiated malonic acid: heat-bath algorithmic cooling

phase difference between the states with and without anyon braiding, which is equivalent to two successive particle exchanges, is observed. This is different from the

Heat Bath Algorithmic Cooling with Spins: Review and Prospects

\pi\times 2

Experimentally superposing two pure states with partial prior knowledge

and

Randomized benchmarking of quantum gates implemented by electron spin resonance.

2\pi \times 2

Estimating the Coherence of Noise in Quantum Control of a Solid-State Qubit

phases for Fermions and Bosons after two successive particle exchanges, and is consistent with the fractional statistics of anyons.

Optimal experimental dynamical decoupling of both longitudinal and transverse relaxations

Accurate and efficient control of quantum systems is one of the central challenges for quantum information processing. Current state-of-the-art experiments rarely go beyond 10 qubits and in most cases demonstrate only limited control. Here we demonstrate control of a 12-qubit system, and show that the system can be employed as a quantum processor to optimize its own control sequence by using measurement-based feedback control (MQFC). The final product is a control sequence for a complex 12-qubit task: preparation of a 12-coherent state. The control sequence is about 10% more accurate than the one generated by the standard (classical) technique, showing that MQFC can correct for unknown imperfections. Apart from demonstrating a high level of control over a relatively large system, our results show that even at the 12-qubit level, a quantum processor can be a useful lab instrument. As an extension of our work, we propose a method for combining the MQFC technique with a twirling protocol, to optimize the control sequence that produces a desired Clifford gate.Headline: Bootstrapping a 12-qubit quantum processorRealizing high accuracy control of quantum systems represents a crucial ingredient in building large-scaled quantum computers. An international team of researchers led by Raymond Laflamme at Canada’s Institute for Quantum Computing has succeeded in manipulating a 12-qubit nuclear magnetic resonance quantum processor with unprecedented precision. The researchers build a closed-loop pulse auto-tunning setup which employs the controlled system itself to optimize its own pulses. This gives to the benefits of more efficient pulse optimization and more robustness to system uncertainties. Because that the experiment achieves high level of individual controls over all of the qubits, it is at the cutting edge of experimental quantum computing. The experimental techniques are ready to be transferred to other quantum technologies, such as nitrogen-vacancy centers, trapped ions or superconducting circuits.

Towards quantum supremacy: enhancing quantum control by bootstrapping a quantum processor

The ability to perform quantum error correction is a significant hurdle for scalable quantum information processing. A key requirement for multiple-round quantum error correction is the ability to dynamically extract entropy from ancilla qubits. Heat-bath algorithmic cooling is a method that uses quantum logic operations to move entropy from one subsystem to another and permits cooling of a spin qubit below the closed system (Shannon) bound. Gamma-irradiated,