The research group aims to explore fundamental features of quantum mechanics, including quantum superposition and quantum entanglement, and to exploit these features for the development of various types of quantum technologies. Currently, the research group focuses on quantum sensing and quantum metrology, quantum simulation, fundamental test of quantum mechanics. The research group is also affiliated with HUST-UULM International Joint Laboratory on Quantum Sensing and Quantum Metrology (IQSQM) which represents a joint research center between Huazhong University of Science and Technology and Ulm University (Germany).The International Joint Laboratory has built two experiment platforms for solid-state spin quantum control and micro/nano quantum sensing &quantum metrology, which aim to develop new techniques for quantum control of solid-state spin system and new methods for quantum sensing and quantum metrology with superior performance. Since the start of the research group in October 2014, it has been developing fast under the support of National Youth 1000-talent program, National Science Foundation of China (NSFC).
Quantum Sensing & Quantum Metrology
Quantum sensing exploits quantum properties of a quantum system to perform a measurement of a physical quantity (for example magnetic field, electric field, temperature, force and strain) with a sensitivity or resolution that may surpass the limit for classical methods. The research group is mainly working on micro/nano scale quantum sensing, namely developing new methods for quantum sensing and quantum metrology with quantum enhanced measurement sensitivity and high spatial resolution. The long-term research topics in this direction include: quantum enhanced magnetic resonance spectroscopy, portable and compact quantum sensor, in vivo quantum sensing, quantum precision measurement to test fundamental problems in quantum mechanics.
Due to its superior coherent and optical properties at room temperature, the nitrogen-vacancy (NV) center in diamond has become a promising quantum probe for nanoscale quantum sensing. However, the application of NV containing nanodiamonds to quantum sensing suffers from their relatively poor spin coherence times. The research group demonstrates energy efficient protection of NV spin coherence in nanodiamonds using concatenated continuous dynamical decoupling, which exhibits excellent performance with much less stringent microwave power requirement. When applied to nanodiamonds in living cells, the research groupis able to extend the spin coherence time by an order of magnitude to the T1-limit of up to 30μs. Further analysis demonstrates concomitant improvements of sensing performance by orders of magnitudes. The work represents an important step towards in vivo quantum sensing using nanodiamond [Protecting quantum spin coherence of nanodiamonds in living cells, arXiv: 1710.10744].
The research team has put intensive efforts in developing new protocols for micro/nano scale quantum sensing. The team presented a scheme to detect the charge recombination rate in a radical pair reaction on the single-molecule level under ambient conditions by using single nitrogen-vacancy center spin in diamond. [Scheme for detection of single molecule radical pair reaction using spin in diamond, Phys. Rev. Lett. 118, 200402 (2017)]; a proposal for a hybrid device composed of thin film layers of diamond with color centres and piezoactive elements for the transduction and measurement of physical signals, which can achieve significant improvements in sensitivity over the pure diamond-based approach in combination with Scientific Research 80 nanometre-scale spatial resolution [Hybrid sensors based on colour centres in diamond and piezoactive layers, Nature Communications 5, 4065 (2014)]; a proposal for highly efficient magnetometry using single atom, which was implemented in collaboration with Prof. Ch. Wunderlich‟s experiment group [Ultrasensitive magnetometer using a single atom, Phys. Rev. Lett. 116, 240801 (2016)].
Scalable Quantum Control &Quantum Simulation
Quantum simulation provides a platform for the study of fundamental problems in many fields, such as condensed-matter physics, atomic physics, high-energy physics, quantum chemistry and cosmology. The central challenge in the field of quantum simulation is the scalability of a quantum simulator and quantum engineering of scalable quantum system for the simulation of novel physics. The research group focuses on two promising scale quantum systems for the implementation of quantum simulation, namely ultracold atomic systems and solid-state spin system. The long-term research topics in this direction include: engineer novel quantum phases (e.g. topological matter) in ultracold atomic systems, new architecture for topological quantum computation, Floquet quantum engineering in solid-state spin systems, novel hybrid quantum system for scalable quantum information processing, many-body quantum physics and the application in quantum memory and quantum metrology.
The research team proposed to realize topological quantum matter (including quantum anomalous Hall effect, chiral d-wave superfluids, Weyl points and nodal topological superfluids)[Shaping topological properties of the band structures in a shaken optical lattice, Phys. Rev. A.90, 051601(R) (2014); Chiral d-Wave Superfluid in Periodically Driven Lattices, Phys. Rev. Lett. 115, 225301 (2015); Weyl points and topological nodal superfluids in a face-centered-cubic optical lattice, Phys. Rev. B. 96, 035145(2017)] and to explore topological physics (including topological system with glide symmetry, charge fractionalization phenomenon) [Two-leg Su-Schrieffer-Heeger chain with glide reflection symmetry, Phys. Rev. A 95, 061601(R) (2017); Nodal Brillouin-zone boundary from folding a Chern insulator, Phys. Rev. A 95, 053615 (2017)], in highly controllableultracold atomic systems which is feasible by the state-of-art experiment technology. The research team also collaborated with Prof. Jing Zhang‟s group at Shanxi University to realize the two-dimensional spin-orbit coupling for the first time in experiment [Experimental realization of two-dimensional synthetic Scientific Research 81 spin–orbit coupling in ultracold Fermi gases, Nature Physics 12, 540 (2016)].
The research team proposed a new solid-state architecture for a scalable quantum simulator that consists of strongly interacting nuclear spins attached to the diamond surface. The system can be engineered to simulate a wide variety of strongly correlated spin models. Owing to the superior coherence time of nuclear spins and nitrogen-vacancy centers in diamond, the proposal offers new opportunities towards large-scale quantum simulation at ambient conditions of temperature and pressure [A large-scale quantum simulator on a diamond surface at room temperature, Nature Physics 9, 168 (2013)].
The research team also proposed robust and scalable quantum information processor based on solid-state spin systems [Proposal for high-fidelity quantum simulation using a hybrid dressed state, Phys. Rev. Lett. 115, 160504 (2015); Entangling distant solid-state spins via thermal phonons, Phys. Rev. B 96, 245418 (2017)]. The research team experimentally observed Floquet Raman transitions in the weakly driven solid-state spin system of nitrogen-vacancy center in diamond. The periodically driven spin system simulates a two-band Wannier-Stark ladder model and allows us to observe coherent spin state transfer arising from Raman transition mediated by Floquet synthetic levels. It leads to the prediction of analogphoton-assisted Floquet Raman transition and dynamical localization in a driven two-level quantum system. The demonstrated rich Floquet dynamics offers new capabilities to achieve effective Floquetcoherent control of a quantum system with potential applications in various types of quantum technologies based on driven quantum dynamics [Observation of Floquet Raman transition in a driven solid-state spin system, submitted (2018)].
Group Members
The current team members include Prof. Jianming Cai, Prof. Linchuan Xiang, Asso. Prof. Shaoliang Zhang, and Prof. Martin B. Plenio (full professor at Ulm University, guest professor at HUST, and co-director of IQSQM), Prof. Fedor Jelezko (full professor at Ulm University, and co-director of IQSQM). The team has 4 postdoctoral research fellows, 8 PhD students and 6 master students.
