Monday, March 13, 2017 — 2:30 PM EDT

### Trapped-ion quantum logic with near-field microwave-driven gates

#### David Allcock, National Institute of Standards and Technology, Boulder

Hyperfine qubits in laser-cooled trapped atomic ions are one of the most promising platforms for general-purpose quantum computing. Magnetic field-insensitive ‘clock states’ and near-infinite lifetimes allow for minute-long memory coherence times as well as qubit frequencies that are in the convenient microwave domain [1]. Most work on these qubits has so far focussed on using lasers for gate operations, however there are several schemes that offer the prospect of performing all coherent operations using purely electronic methods [2,3].

Friday, March 10, 2017 — 11:45 AM EST

### Fabrication of Diamond Based Fabry-Perot Cavities: Boring is beautiful

#### Madelaine Liddy, IQC

Nitrogen-vacancy (NV) centers in diamond are promising candidates for acting as the nodes in a quantum network. Previous work has demonstrated the entanglement between two NV centers over a distance of 1.3km for the loophole-free bell test in 2015.

Thursday, March 9, 2017 — 10:30 AM EST

### The Power of Randomized and Quantum Computation

#### Shalev Ben-David, Massachusetts Institute of Technology

Randomized and quantum computing offer potential improvements over deterministic algorithms, and challenge our notion of what should be considered efficient computation. A fundamental question in complexity theory is to try to understand when these resources help; on which tasks do randomized or quantum algorithms outperform deterministic ones?

In this talk, I will describe some of my work investigating this question, primarily in the query complexity (blackbox) model.

Monday, March 6, 2017 — 2:30 PM EST

### Quantum Entanglement, Sum-of-Squares and the Log-Rank Conjecture

#### Pravesh Kothari, Princeton University

This talk will be about a sub-exponential time algorithm for the Best Separable State (BSS) problem. For every constant \eps>0, we give an exp(\sqrt(n) \poly log(n))-time algorithm for the 1 vs 1-\eps BSS problem of distinguishing, given an n^2 x n^2 matrix M corresponding to a quantum measurement, between the case that there is a separable (i.e., non-entangled) state \rho that M accepts with probability 1, and the case that every separable state is accepted with probability at most 1-\eps.

Thursday, March 2, 2017 — 1:30 PM EST

### Harnessing quantum systems with long-range interactions

#### Zhexuan Gong, University of Maryland, College Park

A distinctive feature of atomic, molecular, and optical systems is that interactions between particles are often long-ranged. Together with control techniques from quantum optics, these long-range interacting systems could be harnessed to achieve faster quantum information processing and to simulate novel quantum many-body phenomena. A

Thursday, March 2, 2017 — 12:00 PM EST

### Expected communication cost of distributed quantum tasks

#### Penghui Yao, University of Maryland, Baltimore

Data compression is a fundamental problem in quantum and classical information theory. A typical version of the problem is that the sender Alice receives a classical or quantum) state from some known ensemble and needs to transmit it to the receiver Bob with average error below some specified bound. We consider the case in which the message can have a variable length and goal is to minimise its expected length. For the classical case, this problem has a well-known solution given by the Huffman coding.

Tuesday, February 28, 2017 — 12:00 PM to 1:00 PM EST

This is the second of the Intellectual Property (IP) Management Lunch and Learn Lecture Series. We are bringing in thought leaders in the protection and management of intellectual property, including many years of experience in relevant areas of information technology.

This session will be led by Jeff Wong.

Monday, February 27, 2017 — 2:00 PM EST

### Progress and challenges in designing a universal Majorana quantum computer

#### Torsten Karzig, Microsoft Research Station Q

I will discuss a promising design proposal for a scalable topological quantum computer. The qubits are envisioned to be encoded in aggregates of four or more Majorana zero modes, realized at the ends of topological superconducting wire segments that are assembled into superconducting islands with significant charging energy. Quantum information can be manipulated according to a measurement-only protocol, which is facilitated by tunable couplings between Majorana zero modes and nearby semiconductor quantum dots.

Monday, February 27, 2017 — 9:30 AM EST

### Harnessing quantum entanglement

#### Laura Mancinska, University of Bristol

The phenomenon of entanglement is one the key features of quantum mechanics. It can be used to attain functionality lying beyond the reach of classical technologies. In practice, however, finding the best way of harnessing entanglement for a given task is extremely challenging and one is often forced to resort to ad hoc methods. The mathematical structure of entanglement- enabled strategies is poorly understood and many basic questions remain open. This lack of understanding has prevented us from fully exploiting the advantages that entanglement can offer for operational tasks.

Friday, February 24, 2017 — 11:45 AM EST

### Epitaxial Growth of Silicon Nanowires and Niobium Thin Films for Magnetic Resonance Force Microscopy

#### Michele Piscitelli

Magnetic Resonance Force Microscopy (MRFM) is an imaging technique enabling the acquisition of magnetic resonance images at nanometer scales. Single electron spin sensitivity has been demonstrated [1] and current MRFM research is focused on working towards achieving single nuclear spin sensitivity. In general, an MRFM setup requires a nano-scale source of high magnetic field gradients to modulate the sample spins and a cantilever-based detection scheme to measure their magnetic moment.

Thursday, February 23, 2017 — 7:00 PM EST

### Short film festival + public lecture by Martin Laforest

Join us for a night of film and science. The Institute for Quantum Computing has partnered with the Centre for Quantum Technologies in Singapore to host a festival for quantum-inspired films. The screening of the top 10 short films will be followed by a lecture by Senior Manager, Scientific Outreach, Martin Laforest about the applications of quantum devices. He will delve into what we know quantum devices will be used for (that will affect everyone) and where researchers are hoping they will be used in the future.

Thursday, February 23, 2017 — 9:30 AM EST

### Quantum entanglement through the lens of computation and cryptography

Henry Yuen, University of California at Berkeley

Quantum entanglement was once a philosophical peculiarity in physics — Einstein famously derided it as spooky action at a distance. Alongside wave/particle duality and the uncertainty principle, entanglement was just another bizarre feature of quantum mechanics. However, the study of quantum computation and quantum information has established entanglement as central to the story that connects quantum physics, computer science, and information theory.

Wednesday, February 15, 2017 — 11:30 AM EST

### Carbon nanotube forest from energy conversion to MEMS devices and a laser based single sub 10nm particle analyzer: new developments in nanotechnology

#### Mehran Vahdani, The University of British Columbia

Vertically aligned carbon nanotubes, so called CNT forests, have unique properties that make them excellent candidates in a wide variety of applications ranging from nanotechnology to electronics and photonics.

Tuesday, February 14, 2017 — 12:00 PM to 1:00 PM EST

This is the first of the Intellectual Property (IP) Management Lunch and Learn Lecture Series. We are bringing in thought leaders in the protection and management of intellectual property, including many years of experience in relevant areas of information technology.

This session will be led by Tom Hunter.

Monday, February 13, 2017 — 4:00 PM EST

### The mathematics of non-local games

#### William Slofstra, Institute for Quantum Computing

Non-local games are an important subject in quantum information. They provide relatively simple experimental scenarios for testing the axioms of quantum mechanics, and have been proposed for other practical applications, especially in device-independent cryptography. However, we do not know how to answer many of the basic mathematical questions about non-local games.

Monday, February 13, 2017 — 2:30 PM EST

### An inversion-symmetry-broken order inside the pseudogap region of a cuprate revealed by optical second harmonic generation

#### Liuyan Zhao, University of Michigan

The phase diagram of cuprate high-temperature superconductors features an enigmatic pseudogap region that is characterized by a partial suppression of low-energy electronic excitations. In order to understand its microscopic nature, it is imperative to identify the full symmetries both prior to and within the pseudogap region. In this talk, I will describe our experimental results of symmetry properties on YBa2Cu3Oy across a wide temperature and doping range using a recently developed nonlinear optical rotational anisotropy technique.

Friday, February 10, 2017 — 2:00 PM EST

### Quantum entanglement for precision sensing with atoms and light

#### Onur Hosten, Stanford University

In the last decades, advances in the level of precision in controlling atomic and optical systems opened up the low-energy precision frontier to fundamental physics tests in addition to yielding new applied sensing technologies. In this talk I will focus on our experiments with cold atoms highlighting some of the most recent developments in the prospect of using quantum entanglement to further improve the precision of atomic and optical sensors.

Friday, February 10, 2017 — 11:45 AM EST

### Atomic scale study of Dirac materials: graphene and topological insulator (Bi2Se3)

#### Ying Liu

Graphene and topological insulator Bi2Se3 are newly discovered Dirac materials with exotic physical and electronic properties. The molecular beam epitaxy (MBE) and in situ characterization at atomic scale of the materials are demonstrated in this talk[1][2]. Artificial defects of graphene are created by Ar for extending its functions. Their structural, electronic properties and charge state were studied by scanning tunneling microscopy (STM) and q-plus atomic force microscopy (q-plus AFM ), respectively.

Wednesday, February 8, 2017 — 9:30 AM EST

### Quantum error-correction in black holes

#### Beni Yoshida, Perimeter Institute

It is commonly believed that quantum information is not lost in a black hole. Instead, it is encoded into non-local degrees of freedom in some clever way; like a quantum error-correcting code. In this talk, I will discuss recent attempts to resolve some paradoxes in quantum gravity by using the theory of quantum error-correction.

Monday, February 6, 2017 — 2:00 PM EST

### Quantum experiments exploiting the radiation pressure interaction between light and matter

#### Simon Gröblacher, Delft University of Technology

Mechanical oscillators coupled to light via the radiation pressure force have attracted significant attention over the past years for allowing tests of quantum physics with massive objects and for their potential use in quantum information processing. Recently demonstrated quantum experiments include entanglement and squeezing of both the mechanical and the optical mode.

Friday, February 3, 2017 — 2:00 PM EST

### Entanglement in a synthetic quantum magnet made of hundreds of trapped ions

#### Justin Bohnet, National Institute of Standards and Technology, Boulder

Entanglement between individual quantum objects exponentially increases the complexity of quantum many-body systems, such that models with more than 40 quantum bits cannot be fully studied using conventional techniques on classical computers. To make progress at this frontier of physics, Feynman’s pioneering ideas of quantum computation and quantum simulation are now being pursued in a wide variety of well-controlled platforms.

Friday, February 3, 2017 — 10:30 AM EST

### Research with very cold and ultra-cold neutrons at the Institute Laue Langevin in Grenoble

#### Peter Geltenbort, Institute Laue Langevin, Grenoble

Wednesday, February 1, 2017 — 3:00 PM EST

Vincent Russo of the Department of Computer Science is defending his thesis:

Extended nonlocal games

Vincent is supervised by IQC faculty members John Watrous and Michele Mosca.

Wednesday, February 1, 2017 — 11:45 AM EST

### Extended Learning Graphs for Triangle Finding

#### Mathieu Lauriere, New York University, Shanghai

In this talk we present new quantum algorithms for Triangle Finding improving its best previously known quantum query complexities for both dense and spare instances. For dense graphs on n vertices, we get a query complexity of O(n^{5/4}) without any of the extra logarithmic factors present in the previous algorithm of Le Gall [FOCS’14]. For sparse graphs we also improve some of the results obtained by Le Gall and Nakajima [ISAAC’15].

Friday, January 27, 2017 — 11:45 PM EST

### Airborne demonstration of a QKD payload receiver

#### Chris Pugh, IQC

We demonstrate the viability of components of a quantum receiver satellite payload by successfully performing quantum key distribution in an uplink configuration to an airplane. Each component has a clear path to flight for future satellite integration.