My PhD and post-doctoral research have focused on fully exploiting the multi-mode nature of a photon for the field of quantum information. I have specific expertise in high-dimensional quantum states of light—from their generation and control, to their precise measurement and application in a broad range of quantum imaging and communication protocols. Below, I summarize my main research contributions thus far.

1. High-dimensional quantum states of light: generation, measurement, and control

As part of my PhD thesis, I helped pioneer a high-dimensional quantum state (qudit) sorter that acts as a beam splitter for single photons carrying orbital angular momentum [1]. Using this device, I implemented a new method for efficiently measuring large quantum states that used weak measurements for quantum tomography [2]. In parallel, I helped develop a method for the rapid generation of photonic qudits using a digital micro-mirror device (DMD) that improved on existing speeds by two orders of magnitude [3]. My more recent work has focused on developing methods for the precise manipulation of high-dimensional quantum states, such as a high-dimensional entanglement router [4] and cyclic transformations for photonic qudits [5].

2. Multi-photon entanglement in high dimensions

My post-doctoral research has concentrated on combining my knowledge of high-dimensional quantum information with the field of multi-photon entanglement. In a recent experiment, I created the first three-photon state entangled in a high-dimensional Hilbert space [6]. This state exhibited a previously unobserved asymmetric entanglement structure, with two particles entangled in more levels than the third. In addition, I helped develop an algorithm that found quantum experiments for creating a vast family of new, high-dimensional multi-photon entangled states [7]. Currently, I am in the final stages of an experiment where we are implementing one of these experiments to demonstrate violations of local-realism with a three-dimensional Greenberger-Horne-Zeilinger (GHZ) state [8].

3. Multi-level quantum communication through turbulence

Combining the generation and measurement techniques developed during my PhD, I demonstrated a lab-scale high-dimensional QKD protocol that used twisted light for encoding information [9]. I have extensively studied the evolution of high-dimensional quantum states in strongly scattering turbulence [10, 11], with specific application towards performing high-dimensional QKD through the atmosphere. My research work in Vienna has built on this effort by establishing multi-level communication links over large scale distances, and showing their feasibility for macroscopic quantum entanglement experiments. Together with my colleagues, I demonstrated communication links with spatial modes of light over 3km in Vienna [12] and very recently, over a record distance of 143km in the Canary Islands [13].

4. Quantum-enhanced imaging

In addition to quantum cryptography, my PhD research has had a parallel focus on the use of quantum states of light for quantum-enhanced imaging and metrology. I developed a new type of quantum-secured imaging protocol which borrowed principles from QKD to provide security in an active imaging system [14]. I also demonstrated a holographic quantum ghost-imaging technique that used a hologram as an image sorter for efficiently identifying an object [15]. Along with my colleagues, I developed a compressive sensing-based object-tracking protocol that used entangled photons to efficiently track a moving object [16]. In addition, I helped design an enhanced quantum phase estimation technique using N00N states that combined quantum and classical advantages [17].


[1]  M. Mirhosseini, M. Malik, Z. Shi & R. W. Boyd, Nature Commun. 4:2781 (2013)

[2]  M. Malik et al., Nature Commun. 5:3115 (2014)

[3]  M. Mirhosseini et al., Opt. Exp. 21, 30204–30211 (2013)

[4]  M. Erhard, M. Malik & A. Zeilinger, arXiv: 1605.05947 (2016)

[5]  F. Schlederer, M. Krenn, R. Fickler, M. Malik & A. Zeilinger, New J. Phys. 18, 043019 (2016)

[6]  M. Malik et al., Nat. Photonics 10, 248 (2016)

[7]  M. Krenn, M. Malik, R. Fickler, R. Lapkiewicz & A. Zeilinger, Phys. Rev. Lett. 116, 090405 (2016)

[8]  M. Erhard, M. Malik, M. Huber, M. Krenn & A. Zeilinger, In preparation (2016)

[9]  M. Mirhosseini et al., New J. Phys. 17, 033033 (2015)

[10]  M. Malik et al., Opt. Exp. 20, 13195–13200 (2012)

[11]  B. Rodenburg et al., New J. Phys. 16, 033020 (2014)

[12]  M. Krenn et al., New J. Phys. 16, 113028 (2014)

[13]  M. Krenn et al., PNAS, doi:10.1073/pnas.1612023113 (2016)

[14]  M. Malik, O. S. Magaña-Loaiza & R. W. Boyd, Appl. Phys. Lett. 101, 241103 (2012)

[15]  M. Malik, H. Shin, M. N. O’Sullivan, P. Zerom & R. W. Boyd, Phys. Rev. Lett. 104, 163602 (2010)

[16]  O. S. Magaña-Loaiza, M. Malik, G. A. Howland, J. C. Howell & R. W. Boyd, Appl. Phys. Lett. 102, 231104 (2013)

[17]  H. Shin, O. S. Magaña-Loaiza, M. Malik, M. N. O’Sullivan & R. W. Boyd, Opt. Exp. 21, 2816 (2013).