## Cavendish Quantum Colloquium

This series of colloquia in the Cavendish laboratory aims to cover all aspects of modern quantum many-body physics. It is broadly aligned with our research themes of ** Emergent Quantum Phenomena (EQP)** and

**and as such will feature talks on both fundamental many-body physics as well as their exploitation in devices. It therefore covers all aspects of quantum phenomena in condensed matter and synthetic many-body systems, and their theoretical description.**

*Quantum Devices and Measurements (QDM)*As a consequence, the aim for these colloquia is to be accessible to a wider audience compared to a typical group seminar.

### All are welcome

**Upcoming talks - 2019/2020**

### Lent term 2020

## 28.02.20 Prof. Antoine Browaeys - *14:30 Pippard Lecture Theatre*

*Institut d’Optique, Laboratoire Charles Fabry*

### Many-body physics with arrays of individual Rydberg atoms

This talk will present our effort to control and use the dipole-dipole interactions between cold Rydberg atoms in order to implement spin Hamiltonians useful for quantum simulation of condensed matter situations. In our experiment, we trap individual atoms in arrays of optical tweezers separated by few micrometers and excite them to Rydberg states using lasers. The arrays are produced by a spatial light modulator, which shapes the dipole trap beam. We can create almost arbitrary geometries of the arrays with near unit filling in two and three dimensions up to about 70 atoms. We have demonstrated the coherent energy exchange in chains of Rydberg atoms resulting from their resonant dipole-dipole interaction and its control by addressable lasers. This interaction realizes the XY spin model. We use this control to study elementary excitations in a di-merized spin chain featuring topological properties, thus implementing the Su-Schrieffer-Heeger model. We have observed the edge states in the topological condition and their hybridization by studying their dynamics. We explored the regime beyond the linear response by adding several excitations, which act as hard-core bosons. Using the van der Waals interaction between atoms, we have also implemented the quantum Ising model in one-dimensional chains with periodic boundary conditions and two-dimensional arrays containing up to about 50 atoms. We measure the dynamics of the excitation for various strengths of the interactions and compare the data to numerical simulations of this many-body system. This control of an ensemble of interacting Rydberg atoms demonstrates an interesting platform for quantum simulation using neutral atoms, complementary to the other platforms based on ions, magnetic atoms or dipolar molecules.

### Easter term 2020

## 24.04.20 Prof. Jon Simon - *14:30 Small Lecture Theatre*

*University of Chicago*

### Making Quantum Matter from Light

In this talk I will discuss ongoing efforts at UChicago to explore matter made of light. I will begin with a broad introduction to the challenges associated with making matter from photons, focusing specifically on (1) how to trap photons and imbue them with synthetic mass and charge; (2) how to induce photons to collide with one another; and (3) how to drive photons to order, by cooling or otherwise. I will then provide as examples two state-of-the-art photonic quantum matter platforms: microwave photons coupled to superconducting resonators and transmon qubits, and optical photons trapped in multimode optical cavities and made to interact through Rydberg-dressing. In each case I will describe a synthetic material created in that platform: a Mott insulator of microwave photons, stabilized by coupling to an engineered, non-Markovian reservoir, and a Laughlin molecule of optical photons prepared by scattering photons through the optical cavity. Indeed, building materials photon-by-photon will provide us with a unique opportunity to learn what all of the above words mean, and why they are important for quantum-materials science. Finally, I will conclude with my view of the broad prospects of photonic matter in particular, and of synthetic matter more generally.

## 06.05.20 (Wednesday) Prof. Norman Yao - *14:00 Small Lecture Theatre*

*University of California Berkeley*

### Title TBC

Abstract TBC

## 22.05.20 Prof. Jack Harris - *14:30 Small Lecture Theatre*

*Yale University*

### Single-phonon quantum optomechanics with superfluid helium

Searching for quantum effects in macroscopic objects typically requires low temperatures, low loss, and high-precision readout. Superfluid helium offers many advantages in these regards. I will describe two experiments using superfluid optomechanical devices. In the first, superfluid fills a Fabry-Perot optical cavity. The cavity is used to monitor the quantum fluctuations of the superfluid's acoustic modes and to make real-time detection of individual phonons. The second experiment uses magnetic levitation to suspend a mm-scale drop of superfluid in vacuum. I will describe preliminary measurements of the drops' formation, trapping, evaporative cooling, and of their mechanical and optical resonances

## 05.06.20 Prof. Cindy Regal - *14:30 Small Lecture Theatre*

*JILA, University of Colorado Boulder*

### Towards connecting microwave and optical photons with mechanical motion

Superconducting qubits have become a powerful resource for the creation of arbitrary quantum states. Yet optical links are the best way to preserve a quantum state over long distances. I present work in which we are exploring an efficient and low-added noise link between the microwave and optical domains via the motion of a micromechanical SiN membrane. Recent results include the demonstration of a nearly 50% efficient classical converter at dilution refrigerator temperatures, and harnessing electro-optic correlations for suppression of added thermal noise. I will discuss general challenges of connecting these disparate domains of the electromagnetic spectrum, and how techniques to control mechanical mode spectra are key to realizing mechanically-mediated transduction.

**Past talks**

### Lent term 2020

## 14.02.20 Prof. Anthony Laing - *14:30 Pippard Lecture Theatre*

*University of Bristol*

### Special purpose quantum computers in integrated photonics

Modelling the dynamics of quantum mechanical systems, including molecules, is generally an intractable problem for classical computers. However, as proposed by Feynman, the exponential computational overheads associated with these simulations may be overcome by utilising a controllable quantum system that can be programmed to mimic the quantum behaviour of a model of interest.

Integrated photonics has been established as a platform for quantum information processing. Recent progress in integrated photonics includes programmable circuitry, the integration of photon sources, and single photon detection. Together with high-speed and low-loss photonic switches, a versatile class of photonic quantum simulators becomes a realistic prospect.

It is possible that the demands on error correction for specialised quantum computers, such as quantum simulators, could be much lower than those for universal digital quantum computers. For photonics, it is believed that a quantum simulator that can generate and process more than 50 pure photons will significantly outperform a supercomputer.

I will discuss experimental demonstrations of quantum photonics as a simulation platform for molecular quantum dynamics. I will cover recent developments in integrated quantum photonics that will help us scale these simulation devices. And I will cover classical emulations techniques that provide important benchmarks.

## 31.01.20 Prof. Carlo Beenakker - *15:00 Small Lecture Theatre*

*Instituut-Lorentz, Leiden University*

### Majorana edge modes in topological superconductors

Two-dimensional superconductors with broken time-reversal symmetry havebeen predicted to support topologically protected chiral edge states, providing a superconducting counterpart to the quantum Hall effect in semiconductors. The edge states carry charge-neutral quasiparticles, coherent superpositions of electrons and holes referred to as "Majorana fermions". We present an overview of electrical and thermal probes of the superconducting edge states, focusing on unique signatures of their Majorana nature and on applications for topological quantum computation. In particular, we show how topological qubits can be braided by injecting them into the conducting edge of a superconductor.

## 17.01.20 Prof. Alexandra Olaya-Castro - *14:30 **Pippard** Lecture Theatre*

**Department of Physics and Astronomy,***University College London*

### Vibronic coherence in light-harvesting systems

There is mounting evidence that vibronic coupling and the associated quantum mechanical exchange of energy between excitonic and some vibrational motions could be at the heart of the counterintuitive long-lived coherence beating probed in Two-dimensional ultrafast spectroscopy of photosynthetic complexes. Under this hypothesis, specific quasi-coherent intramolecular vibrations influence excited-state dynamics through the formation of joint quantum states of excitonic and vibrational degrees of freedom. The exact influence such vibronic coupling on excited state dynamics is however not fully understood. In this talk I will discuss implications of coherent vibronic coupling for understanding non-trivial quantum effects during energy transfer, energy conversion and synchronisation processes in prototype light-harvesting systems as well as a quantum-optical approaches to probe the quantum coherent nature of the vibronic interactions in such systems.

### Michaelmas term 2019

## 06.12.19 Prof. Dimitris G. Angelakis - *14:30 Small Lecture Theatre*

*CQT Singapore and TUC Crete, Greece*

### Quantum supremacy with generic analog quantum simulators and applications in condensed matter and machine learning

Quantum advantage, or quantum supremacy, is the ability of near-term quantum devices to outperform classical computers at some tasks. One prominent example of such tasks is to sample from the output distribution of large-scale random quantum circuits. In this work, we show that the same sampling complexity can be achieved from driven analog quantum processors, with significantly less stringent requirements for coherence and control on the quantum hardware, and with direct applications in probing quantum phases of matter and in machine learning. Specifically, we show that signatures of quantum supremacy, as proposed in the context of random dynamics, can be used as an accessible order parameter to probe the driven many-body localization phase transition. For machine learning, we show how this driven analog system can be trained to learn distributions of complex classical data using external feedback loops, where the learning performance solely depends on the quantum phase of the system. Our proposal is generic to driven quantum many-body systems and compatible with existing or near-term quantum systems. [arXiv:1906.03860]

1. P. Roushan, et al., , “Spectral signatures of many-body

localization with interacting photons” in Science, 01 Dec 2017: Vol.

358, Issue 6367, 2017

2. J. Tangpatinanon, et. al., “Quantum supremacy in analog quantum

simulators and applications in material science and machine learning”,

arXiv: 1906.03860

## 22.11.19 Prof. Tracy Northup - *14:30 Small Lecture Theatre*

*Institute for Experimental Physics, University of Innsbruck*

### Trapped-ion interfaces for quantum networks

Future quantum networks offer a route to quantum-secure communication, distributed quantum computing, and quantum-enhanced sensing. The applications of a given network will depend on the capabilities available at its nodes, which may be as simple as quantum-state generation and measurement or as advanced as universal quantum computing. Here, we focus on quantum nodes based on trapped ions, an experimental platform with which high-fidelity state preparation, gate operations, and readout have been demonstrated. By coupling trapped ions to the mode of an optical resonator, we construct a coherent interface between single ions and single photons. The building blocks of this interface, probabilistic ion-photon entanglement and deterministic ion-photon state transfer, will be introduced. I will present ongoing work to transfer quantum states between remote trapped-ion systems, highlighting the experimental challenges on the road to scalable networks.

## 08.11.19 Prof. Jake Taylor - *14:00 Small Lecture Theatre*

**Joint Quantum Institute, University of Maryland**

### Building a dark matter wind chime

Galactic and cosmological observations strong suggest the existence of a substantial amount of non-luminous matter. This dark matter could take many forms; the only strong constraints know at present are its approximate density (about one hydrogen atom mass per cubic centimeter in our galaxy) and that it gravitates. Here we consider the observable consequences of particulate dark matter with no standard model coupling, i.e., particles that only gravitate. We find that modern optomechanical detectors, now entering the ultra-coherent quantum regime in a variety of experiments worldwide, may be able to directly observe the effects of individual dark matter parts as they stream past the Earth. However, to achieve this in the laboratory setting requires making substantial strides in the measurement of massive objects, going well beyond the so-called ‘standard quantum limit’. I discuss how leveraging tools from quantum information science, such as quantum non-demolition measurement and squeezing, can achieve unprecedented sensitivity of massive objects to small impulses. I will discuss the scientific and technological path necessary to yield direct gravitational observation of dark matter in the range of the Planck mass to gram-scale particles.

### Easter term 2019

## 31.05.19 Prof. Philip Kim - *14:30 Small Lecture Theatre*

**Harvard University**

### Exciton Superfluid and Ferromagnetic Superconductivity in Graphene

Superfluid and superconductors are two prototypical examples of quantum condensates of bosonic particles. By controlling the interaction between two fermionic particles, a composite boson can be formed by pairing fermions. A crossover behavior from weak coupling superconducting Bardeen-Cooper-Schrieffer (BCS) pairing to a superfluid Bose-Einstein condensate (BEC) of tightly bound pairs has been expected as a function of the attractive interaction in Fermi systems. In this talk, we will discuss two such examples realized in graphene heterostructures. In the first part of the presentation, we will discuss an experimental demonstration of magnetoexciton condensation. Employing two layers of graphene separated by an atomically thin insulator, we realize a superfluid condensation of magnetic-field-induced excitons across the double layers of graphene probed by Coulomb drag. Here, we observe dissipationless exciton motion in this system across the BEC-BCS phase boundary controlled by the magnetic field.

In the second part of the presentation, we will discuss the recent development of unconventional superconductivity appeared in twisted double graphene bilayers with small twisting angles. We observed that a ferromagnetic correlated insulating state appears by controlling the flatness of the bilayer graphene band using the perpendicular electric field applied by the gate. Upon doping this ferromagnetic insulator, we obtain the superconductivity, whose transition temperature can be controlled by electric fields. Remarkably, we find that increasing in-plane magnetic field increases superconducting transition temperature, suggesting unconventional superconductivity with spin-polarized cooper pairs.

## 09.05.19 Prof. Roser Valenti - *14:30 Small Lecture Theatre*

*Goethe University Frankfurt*

### Challenges and Opportunities in Designing Quantum Materials

Unconventional superconductivity with high critical temperatures,

nematicity, frustrated magnetism, spin-liquid phases or the recently

discussed Kitaev model-based phases are a few examples of exotic states in

correlated materials. One of the big challenges in solid state physics is

the microscopic description of such systems. Moreover, being able to

understand these materials implies the possibility of designing compounds

with desirable properties.

In this talk I will review the world of some families of correlated

materials ranging from unconventional superconductors to frustrated magnets

and present some strategies on how to model them microscopically.

### Lent term 2019

## 01.03.19 Dr. Hannah Price - *14:30 Rayleigh and JJ Thompson Seminar room, Maxwell Building*

**Royal Society University Research Fellow and Birmingham Fellow in Theoretical Physics, University of Birmingham**

### Simulating higher spatial dimensions with atoms and photons

Spatial dimensionality deeply affects the physical phenomena which can emerge in a system. Our physical world has three spatial dimensions, and so condensed matter physicists have long asked what happens when quantum particles are effectively confined to move in 1D, 2D or 3D geometries. However, recent advances in ultracold atomic and photonics systems are now providing ways to go beyond these limitations, in order to simulate the physics associated with four or more effective spatial dimensions. As I will present, the development of techniques such as “synthetic dimensions” and “topological pumping” with photons or atoms can allow us to explore higher-dimensional phenomena, such as the 4D topological quantum Hall effect, for the first time.

## 15.02.19 Prof. David Lucas - *14:30 Rayleigh and JJ Thompson Seminar room, Maxwell Building*

**University of Oxford**

### Quantum logic with trapped ions: precise, fast, networked

The concepts of quantum information processing date back at least 35 years, to the ideas of quantum simulation and computing suggested by Feynman and Deutsch respectively. Experimental progress in the field often appears slow, partly because of the demanding precision required in the elementary logic operations for quantum error correction, partly because of the technical challenges associated with scaling systems up to larger numbers of qubits, and partly because our expectations are coloured by the enormous power and progress of classical computing technology over the last hundred years. I will give a brief survey of the state of the art across the various platforms which are being explored for quantum computing, and show that progress is in fact extremely encouraging. I will then report on recent work in Oxford on improving the precision and speed of quantum logic operations in the ion trap platform, and on building an elementary quantum network to distribute entanglement between two different ion trap "nodes" separated by macroscopic distances.

## 01.02.19 Prof. Andreas Wallraff - *15:00 Small lecture theatre* please note change of time and location

**ETH Zurich**

### Quantum Information Processing with Superconducting Circuits

Superconducting circuits are a prime contender for realizing universal quantum computation and solving noisy intermediate-scale quantum (NISQ) problems on fault-tolerant or non-error-corrected quantum processors, respectively. In this talk, I will present elements of an architecture which allows for fast, high-fidelity, single shot qubit read-out [1], for unconditional reset [2], and can be multiplexed [3]. Integrating multiple qubits in a single device, we evaluate performance metrics such as the single and two-qubit gate fidelity and the qubit readout fidelity. We also test the performance of the architecture in parity measurements with real-time feedback, which is a basic element of a error correcting code. To provide a potential avenue for extending monolithic chip-based architectures for quantum information processing, we employ the circuit elements of our architecture to implement a deterministic state transfer and entanglement generation protocol [1]. Our protocol is based on an all-microwave process, which entangles or transfers the state of a superconducting qubit with a time-symmetric itinerant single photon exchanged between individually packaged chips connected by a transmission line. We transfer qubit states at rates of 50 kHz, absorb photons at the receiving node with near unit probability, and achieve transfer process fidelities and on demand remote entanglement state fidelities of about 80 %. We also show that time bin encoding can be used to further improve these quantum communication metrics [5]. Sharing information coherently between physically separated chips in a network of quantum computing modules may be an essential element for realizing a viable extensible quantum information processing system.

[1] T. Walter et al., Phys. Rev. Applied 7, 054020 (2017)

[2]P. Magnard et al., Phys. Rev. Lett. 121, 060502 (2018)

[3] J. Heinsoo et al., Phys. Rev. Applied 10, 034040 (2018)

[4]P. Kurpiers et al., Nature 558, 264-267 (2018)

[5]P. Kurpiers et al., arXiv:1811.07604 (2018)

## 18.01.19 Dr. Helen Walker - *14:30 Rayleigh and JJ Thompson Seminar room, Maxwell Building* please note change of location this term

**Merlin Instrument Scientist, STFC · Rutherford Appleton Laboratory **

### Playing with perovskites - tuning physics through chemical control

The discovery of a CaTiO3 mineral by Gustav Rose in the Urals in 1839, might have been regarded as unremarkable at the time, but since then the perovskite structure has proved to be extremely versatile. It is currently the subject of intense research by geologists, environmental and materials scientists exploring hybrid organic-inorganic solar cell materials and alternative catalysts, and physicists, who look to exploit this versatility. I will present two very different examples of my research on perovskites. First I will look at the possibility of a square lattice double perovskite being the host to a spin liquid state, and second I will present results pushing the flexibility of the structure in the form of a family of metal organic frameworks, investigating how the magnetism can be tuned, with the aim of crystal engineering new multiferroic materials.

### Michaelmas term 2018

## 30.11.18 Prof. Sid Parameswaran - *14:30* small lecture theatre

**Associate Professor, Rudolf Peierls Centre for Theoretical Physics, University of Oxford **

### Topology, symmetry, and anomalies: investigating domain wall physics in quantum Hall nematic states

I will present recent work on ferromagnetic quantum Hall states that form on (111) surfaces of elemental Bismuth in high magnetic fields. This unusual states of matter combine the topological features of quantum Hall states with orientational symmetry breaking characteristic of nematic order. Recent scanning tunneling microscopy measurements have directly visualized the spontaneous formation of boundary modes between distinct nematic domains and investigated their electronic structure [1]. I will demonstrate that these boundary modes belong to a new class of `symmetry-protected’ Luttinger liquid that arise from the interplay of symmetry-breaking with quantum Hall physics, and that they provide a concrete realization of `anomaly inflow’ [2]. The analysis reveals strikingly different behavior of domain wall transport at quantum Hall filling factor $\nu=1,2$, in striking agreement with the STM results. I will explore implications of these ideas for the global phase diagram of quantum Hall valley nematics [3].

[1] M.T. Randeria, K. Agarwal, B. E. Feldman, H. Ding , Huiwen Ji3 , R. J. Cava , S. L. Sondhi , S. A. Parameswaran, A. Yazdani, under review.

[2]K. Agarwal, M.T. Randeria, A. Yazdani, S.L. Sondhi, S.A. Parameswaran, arXiv:1807.10293.

[3] S.A. Parameswaran and B.E. Feldman, arXiv:1809.09616.

## 16.11.18 Dr. Andrew Jardine - *14:30* small lecture theatre

**Cavendish Laboratory, University of Cambridge **

### Helium Spin-Echo: A Flexible Tool for Studying Nanoscale Processes at Surfaces

Many fundamental and technologically relevant surface processes take place over Angstrom to nanometre length scales and picosecond to nanosecond timescales. However, the combination is extremely challenging to study experimentally; microscopy cannot achieve the necessary time-resolution, whereas spectroscopic experiments generally have poor spatial resolution. In this talk, I will introduce the Helium Spin-Echo technique, a method pioneered at the Cavendish, which has enabled the regime to be accessed experimentally for the first time. The technique involves scattering helium atoms while simultaneously using nuclear spin-polarisation of the atoms to split and recombine the helium wavepackets, giving a reciprocal-space surface-correlation measurement, with sensitivity over the picosecond range. Helium Spin-Echo measurements can be applied to a wide range of surface processes and in many cases have revolutionised our understanding of underlying physical phenomena. I will discuss a series of examples from recent experiments including the rates and mechanisms of nanoscale diffusion, the behaviour arising from complex extended molecules compared to point particles, determination of interaction potentials and rate limiting energy barriers, the transition to quantum transport, and energy exchange rates / vibrational lifetimes giving subsequent insights into friction on the nanoscale.

## 02.11.18 Dr. Akshay Rao - *14:30* small lecture theatre

**EPSRC Early Career Fellow, Winton Advanced Research Fellow, Cavendish Laboratory**

### Probing Non-Equilibrium Dynamics in Energy Materials with Extreme Spatio-Temporal Resolution

The interaction of light with matter is fundamental to the operation of a range of devices such as solar cells, LEDs, photocatalytic, plasmonic and many QI systems. For over 30 years, ultrafast spectroscopy has served as the key tool to understand the dynamics of the quasiparticles mediating light-matter interaction such as excitons, polarons and polaritons. However, to date, ultrafast spectroscopies were designed and largely applied to species dissolved in liquids or homogeneous bulk solids. The advent of nanoscience and thin films materials with nanoscale inhomogeneity and disorder has rendered these ensemble-based methods inadequate and they continue to be used largely because of a lack of alternatives, rather than being particularly suited to address the questions of interest. In this talk I will present first results from a new experimental platform combining unprecedented spatial, temporal, spectral and vibronic sensitivity. This allows us to follow the dynamics and motion of charges, excitons, polaritons and other quasiparticles down to 10nm length scales with 10fs time resolution, while providing few nm spectral resolution as well as information about the coupling between electronic and nuclear degrees of freedom in the system. I will highlight unexpected results including ultrafast long-range motion of photoexcitations in 2D semiconductors, organic molecules and hybrid organic-inorganic systems and how these may be harnessed in novel devices.

## 19.10.18 Prof. Manish Chhowalla - *14:30* small lecture theatre

**Goldsmiths' Professor of Materials Science, University of Cambridge**

### Electrical contacts between three-dimensional metals and two-dimensional semiconductors

As the dimensions of semiconducting channels in field effect transistors (FETs) decrease, the contact resistance of metal-semiconductor interface at the source and drain electrodes dominates the performance. Two dimensional (2D) transitional metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2) have been demonstrated to be excellent semi-conductors for ultra-thin FETs. However, unusually high contact resistance has been observed across the metal-2D TMD interface. We have shown that it is possible to reduce the contact resistance by forming lateral junctions between metallic and semiconducting phases of 2D materials. Recent studies have shown that van der Waals (vdW) contacts formed by graphene on 2D TMDs provide lowest contact resistance. However, vdW contacts between evaporated three-dimensional metal and 2D TMDs have yet to be demonstrated. Here, we report the realization of ultra-clean vdW contacts between 3D metals and single layer MoS2. Using scanning transmission electron microscopy (STEM) imaging, we show that the 3D metal and 2D MoS2 interface is atomically sharp with no detectable chemical interaction, suggesting van-der-Waals-type bonding between the metal and MoS2. We show that the contact resistance of indium electrodes is ~ 800 Ω-μm – amongst the lowest observed for metal electrodes on MoS2 and is translated into high performance FETs with mobility in excess of 160 cm2-V-s-1 at room temperature without encapsulation. We also demonstrate low contact resistance of 220 Ω-μm on 2D NbS2 and near ideal band offsets, indicative of defect free interfaces, in WS2 and WSe2. I will introduce 2D TMDs and their properties and then describe our efforts on making good contacts on 2D semiconductors.

## 4.10.18 Prof. Ali Yazdani - 15:30 small lecture theatre

**Princeton University, Princeton, US**

### Spotting the elusive Majorana under the microscope

Ettore Majorana famously considered that there may be fermions in nature that are their own antiparticle — and then he mysteriously disappeared just after proposing the idea in 1938. In recent years, following pioneering theoretical work of Kitaev and others, we have learned how to engineer materials that harbor quasiparticles that behave similar to fermions Majorana had envisioned. In particular, there has been a focus on one-dimensional topological superconductor that harbor Majorana zero modes (MZM) that can potentially be used to make fault-tolerant topological quantum computation possible.

Recently, we have proposed and implemented a platform for realization of topological superconductivity and MZM in chains of magnetic atoms on the surface of a superconductor [1,2]. In this talk, I will describe this platform and the series of experiments we have performed to establish the presence of these exotic quasi-particle using spectroscopic mapping with the scanning tunneling microscope (STM). [2-4] These include study of the unique spin signature of MZM.[4] Finally, if there is time I will discuss our most recent work on realization of MZM in a platform based on chiral quantum spin Hall edge states. Overall these experiments, illustrate how the power of spectroscopic imaging with the STM can be used to visualize novel quantum states of matter and their exotic quasi-particles.

[1] S. Nadj-Perge et al. PRB 88, 020407 (2013).

[2] S. Nadj-Perge et al. Science 346, 6209 (2014).

[3] B. E. Feldman et al. Nature Physics 13, 286 (2016).

[4] S. Jeon et al. Science 358, 772 (2017).

**Past talks -- Joint Semina****r on ****Emergent Quantum Phenomena**

### Lent term 2017

**2.2.18 Dr. Christian Gross**

*Max Planck Institute for Quantum Optics, Garching, Germany*

Quantum Gas Microscopes - From Textbook Experiments to New Frontiers

**16.2.18 Prof. Achim Rosch**

*Institute for Theoretical Physics, University of Cologne, Germany*

Giant response of weakly driven systems

**9.3.18 Prof. Chris Ford & Prof. Charles Smith **

*SP Group, Cavendish laboratory, Cambridge*

Measuring interacting electrons in low dimensional systems: spin-charge separation and 'replicas & tbd

**16.3.18 Prof. Christos Panagopoulos**

*Nanyang Technological University, Singapore*

Tunable Functional Magnetic Skyrmions at Room Temperature

### Michaelmas term 2017

Fridays, 2pm, new location: small lecture theater, Bragg building

- Friday October 13th:

Cold atoms vs solids: Differences and opportunities

**Dr. Ulrich Schneider** AMOP group, Cavendish Laboratory, Cambridge.

- Friday October 27th:

Concepts and techniques in Magnetism

**Dr. Adrian Ionescu **TFM group, Cavendish Laboratory, Cambridge.

- Friday November 10th:

Introduction to topological phases

**Dr. Benjamin Beri **Cavendish & DAMTP, Cambridge.

- Friday October 13th:

Concepts and techniques in Quantum Matter research at the Cavendish

**Dr. F. Malte Grosch **QM group, Cavendish Laboratory, Cambridge.