Jing-Ning Zhang

Experimental test of the quantum Jarzynski equality with a trapped-ion system

The Jarzynski equality, relating non-equilibrium processes to free-energy differences between equilibrium states, has been verified in a number of classical systems. An ion-trap experiment now succeeds in demonstrating its quantum counterpart.

Quantum implementation of the unitary coupled cluster for simulating molecular electronic structure

In classical computational chemistry, the coupled-cluster ansatz is one of the most commonly used

Time reversal and charge conjugation in an embedding quantum simulator

ab~initio

Phonon arithmetic in a trapped ion system

methods, which is critically limited by its non-unitary nature. The unitary modification as an ideal solution to the problem is, however, extremely inefficient in classical conventional computation. Here, we provide the first experimental evidence that indeed the unitary version of the coupled cluster ansatz can be reliably performed in physical quantum system, a trapped ion system. We perform a simulation on the electronic structure of a molecular ion (HeH

Quantum Simulation of the Quantum Rabi Model in a Trapped Ion

^+

Reconstruction of the Jaynes-Cummings field state of ionic motion in a harmonic trap

), where the ground-state energy surface curve is probed, energies of excited-states are studied and the bond-dissociation is simulated non-perturbatively. Our simulation takes advantages from quantum computation to overcome the intrinsic limitations in classical computation and our experimental results indicate that the method is promising for preparing molecular ground-states for quantum simulation.

Realization of geometric Landau-Zener-Stückelberg interferometry

A quantum simulator is an important device that may soon outperform current classical computations. A basic arithmetic operation, the complex conjugate, however, is considered to be impossible to be implemented in such a quantum system due to the linear character of quantum mechanics. Here, we present the experimental quantum simulation of such an unphysical operation beyond the regime of unitary and dissipative evolutions through the embedding of a quantum dynamics in the electronic multilevels of a 171Yb+ ion. We perform time reversal and charge conjugation, which are paradigmatic examples of antiunitary symmetry operators, in the evolution of a Majorana equation without the tomographic knowledge of the evolving state. Thus, these operations can be applied regardless of the system size. Our approach offers the possibility to add unphysical operations to the toolbox of quantum simulation, and provides a route to efficiently compute otherwise intractable quantities, such as entanglement monotones.

Experimental quantum simulation of fermion-antifermion scattering via boson exchange in a trapped ion

Single-quantum level operations are important tools to manipulate a quantum state. Annihilation or creation of single particles translates a quantum state to another by adding or subtracting a particle, depending on how many are already in the given state. The operations are probabilistic and the success rate has yet been low in their experimental realization. Here we experimentally demonstrate (near) deterministic addition and subtraction of a bosonic particle, in particular a phonon of ionic motion in a harmonic potential. We realize the operations by coupling phonons to an auxiliary two-level system and applying transitionless adiabatic passage. We show handy repetition of the operations on various initial states and demonstrate by the reconstruction of the density matrices that the operations preserve coherences. We observe the transformation of a classical state to a highly non-classical one and a Gaussian state to a non-Gaussian one by applying a sequence of operations deterministically.Mark Um, Junhua Zhang, Dingshun Lv, Yao Lu, Shuoming An, Jing-Ning Zhang, Hyunchul Nha, M. S. Kim4∗ and Kihwan Kim1† Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, P. R. China School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-722, Korea Texas A&M University at Qatar, Education City, P.O. Box 23874, Doha, Qatar QOLS, Blackett Laboratory, Imperial College London, SW7 2AZ, United Kingdom

Experimental Preparation of High NOON States for Phonons

We thank Xiao Yuan, Xiongfeng Ma, Hyunchul Nha, Jiyong Park, Jaehak Lee, and M. S. Kim for useful discussions on the entanglement verification of the ground state. This work was supported by the National Key Research and Development Program of China under Grants No. 2016YFA0301900 and No. 2016YFA0301901 and the National Natural Science Foundation of China Grants No. 11374178, No. 11574002, and No. 11504197, MINECO/FEDER FIS2015-69983-P, Ramon y Cajal Grant No. RYC-2012-11391, and Basque Government IT986-16.

Probabilistic Eigensolver with a Trapped-Ion Quantum Processor

A quantum state is fully characterized by its density matrix or equivalently by its quasiprobabilities in phase space. A scheme to identify the quasiprobabilities of a quantum state is an important tool in the recent development of quantum technologies. Based on our highly efficient vacuum measurement scheme, we measure the quasiprobability