## LPHYS'21. Plenary Speakers:

### Passion Extreme Light and Applications to the Greatest Benefit of Human Kind

#### Gérard Mourou

Nobel Prize Winner

École Polytechnique, Palaiseau, France

gerard.mourou@ensta.fr

##### Abstract:

Extreme-light laser is a universal source providing a vast range of high energy radiations and particlesalong with the highest field, highest pressure, temperature and acceleration. It offers the possibility toshed light on some of the remaining unanswered questions in fundamental physics like the genesis ofcosmic rays with energies in excess of 10 20 eV or the loss of information in black-holes. Using wake-field acceleration some of these fundamental questions could be studied in the laboratory. In addition,extreme-light makes possible the study of the structure of vacuum and particle production in "empty"space which is one of the field’s ultimate goal, reaching into the fundamental QED and possibly QCDregimes.

Looking beyond today’s intensity horizon, we will introduce a new concept that could make possiblethe generation of attosecond-zeptosecond high energy coherent pulse, de facto in x-ray domain, openingat the Schwinger level, the zettawatt, and PeV regime; the next chapter of laser-matter interaction.

### Using light to control electrons that in turn create new light

#### Paul Corkum

University of Ottawa, Ottawa, Canada

paul.corkum@nrc.ca

##### Abstract:

Intense light controlling ionizing electrons is at the heart of attosecond pulse generation. I will describe how pulse generation is influenced by the single electron structure of an atom or multi-electron dynamics; how perturbing the electron re-collision allows attosecond time delays to be measured and how these measurements are consistent with the three-step model of attosecond pulse generation.

Light control of electrons can also generate currents when a fundamental and its second harmonic are appropriately phased. These currents are a source term in Maxwell's equations, giving us precise control of the position, magnitude and direction of currents. We generate ring currents in semiconductors and ionizing gases and we use these currents to generate THz magnetic field transients, (including arrays of magnetic fields). The near-field structure of the THz B-field is very similar to a magnetic Skrymion. The radiated pulse will be electromagnetic flying tori.

### Harnessing Attosecond Quantum Technologies

#### Margaret Murnane

JILA, University of Colorado, Boulder, CO, USA

murnane@jila.colorado.edu#### Henry Kapteyn

JILA, University of Colorado, Boulder, CO, USA

kapteyn@jila.colorado.edu

##### Abstract:

High harmonic quantum light sources provide an exquisite ability to harness and control short wavelength light, with unprecedented control over the spectral, temporal, polarization and orbital angular momentum waveforms. These represent the most-complex coherent electromagnetic fields ever created, controlled on sub-Å spatial scales and sub-attosecond temporal scales, from the UV to the keV photon energy region. These advances are providing powerful new tools for near-perfect x-ray imaging, for coherently manipulating quantum materials using light, and for designing more efficient nanoscale devices.

### Plasma-based soft x-ray lasers: from large single-shot machines to compact high repetition rate devices enabling applications

#### Jorge Rocca

Electrical and Computer Engineering, Colorado State University, Fort Collins, CO, USA

jorge.rocca@colostate.edu

##### Abstract:

Plasma-based soft x-ray lasers (SXRL) enable experiments requiring bright, high energy, pulses of coherent soft x-ray radiation to be conducted in compact set ups. This talk will review how plasma based laboratory soft x-ray lasers, which initially started from plasmas generated by high energy pump lasers that could often fire only several shots per day, evolved into high repetition rate table-top devices that enable numerous applications. New excitation schemes such as transient excitation and more efficient plasma heating schemes have allowed a dramatic reduction of the pump energy required to reach gain saturation. However, the development of soft x-ray lasers has also been limited by the available pump source technology. The introduction of direct discharge pumping using capillary discharges and new advances in high energy ultrashort pulse solid state lasers have made it possible to increase their repetition rate, extend their wavelength range, and generate shorter (ps and sub-ps) pulses. Compact, high power solid state lasers have enabled the operation of gain-saturated compact repetitive x-ray lasers at wavelengths down to λ=6.85 nm in Ni-like Gd. In turn, the development of Joule-level diode-pumped ultrashort pulse optical lasers has made it possible to increase the repetition rate of SXRLs to 100 Hz, with for example an average power of > 0.1 mW at λ=13.9nm. Injection seeding with high harmonic pulses has enabled the soft x ray lasers with practically full spatial and temporal coherence. The application of these lasers in multiple application affecting several different fields including dense plasma diagnostics, nanoscale imaging, nanofabrication, photochemistry and photophysics, and nuclear forensic will be reviewed. Future prospects will be discussed.

**Acknowledgment:**US DOE, NSF, AFOSR, ONR, and DOD Vannevar Bush Faculty Fellowship### The quantum theory of the laser applied to: Bose condensation, radiation from a black hole, the Frölich condensate and COVID-19 virus dynamics

#### Marlan O Scully

Texas A&M University, Princeton, NJ, USA

Baylor University, Waco, TX, USA

scully@tamu.edu

##### Abstract:

The original motivation for developing the quantum master equation for the laser was provided by Glauber [1] who said:

The only reliable method we have of constructing density operators, in general, is to devise theoretical models and to solve the equation of motion for the density operator. These assignments are formidable ones for the case of the laser oscillator and have not been carried out to the date in quantum mechanical terms. The greatest part of the difficulty lies in the mathematical complications associated with the nonlinearity of the device. … It seems unlikely, therefore, that we shall have a quantum mechanically consistent picture of the frequency bandwidth of the laser or of the fluctuations of its output until further progress is made with these problems.

In the present talk, the laser quantum master equation analysis [2] will be shown to provide a useful tool for describing the Bose condensate as an “atom” laser [3] on the one hand and the radiation from atoms falling into a black hole [4] on the other. Furthermore, the dynamics of various problems in biophysics such as Frohlich [5] condensate of collective motion in proteins [6] and calculating the binding energy of the COVID-19 virus to the ACE sites in the body [7], will also be discussed using the quantum theory of the laser formalism.

[1] R. Glauber, Les Houches Lectures, 1964

[2] M. Scully and W. Lamb, PRL, 1964

[3] M. Scully, PRL, 1999

[4] M. Scully et al. PNAS, 2018

[5] Z. Zhang, G. Agarwal and M. Scully, PRL, 2019

[6] H. Fröhlich, Int. J. Quantum Chem., 1968

[7] R. Nessler et al. TBP### Exploring new scientific frontiers with programmable atom arrays

#### Mikhail Lukin

Harvard University, Cambridge, MA, USA

lukin@physics.harvard.edu

##### Abstract:

We will discuss the recent advances involving programmable, coherent manipulation of quantum many-body systems using atom arrays excited into Rydberg states. Specifically, we will describe our recent technical upgrades that now allow the control over 200 atoms in two-dimensional arrays. Recent results involving the realization of exotic phases of matter, study of quantum phase transitions and exploration of their non-equilibrium dynamics will be presented. In particular, we will report on realization and probing of quantum spin liquid states -- the exotic states of matter have thus far evaded direct experimental detection. Finally, realization and testing of quantum optimization algorithms using such systems will be discussed.

### Squeezing, time reversal symmetry, and chiral optics

#### Gerd Leuchs

Max Planck Institute for the Science of Light, Erlangen, Germany

gerd.leuchs@mpl.mpg.de

##### Abstract:

The probably most readily available squeezing of the excitation of a light mode is produced by the Kerr effect. However, the squeezing ellipse is tilted, rendering practical use difficult. A cure was proposed by Kitagawa and Yamamoto [1] already in 1986 turning Kerr squeezing into amplitude squeezing. This method requires a detailed balance between a non-linear phase shift, a linear path length difference and the splitting ratio, a combination, which is not easy to achieve perfectly and the amount of observable and useful squeezing is limited. To maximize the observable Kerr squeezing, the next step was to increase the dimension to two modes and produce e.g. polarization squeezing [2]. The degree of squeezing improved but the ellipse was again tilted so that the interferometric sensitivity was not improved. Now, a new method is being explored, making full use the plethora of rotations of the quantum state on the Poincaré sphere, be it by beam splitters or linear phase shifts. The whole range of possible beam splitter rotations is discussed using time reversal symmetry considerations following G.G. Stokes [3]. A combination of linear and circular birefringent optical elements such as fibers [4] allows one to dream up the new method of making Kerr squeezing more accessible to applications.

[1] M Kitagawa, Y Yamamoto, Phys. Rev. A 34, 3974 (1986)

[2] R Dong, J Heersink, J F Corney et al., Opt. Lett. 33, 116 (2008)

[3] G G Stokes, Cambridge and Dublin Math. J. IV, 1 (1849)

[4] P StJ Russell, R Beravat, G K L Wong, Phil. Trans. R. Soc. A 375, 20150440 (2017)### Secure Communications using Quantum Continuous Variables

#### Philippe Grangier

Laboratoire Charles Fabry, Institut d'Optique Graduate School, Palaiseau, France

philippe.grangier@institutoptique.fr

##### Abstract:

During the last 20 years Quantum Continuous Variables have emerged as a valid and interesting alternative to the usual qubits for quantum information processing. We will briefly review these developments, and focus on continuous variable (CV) quantum key distribution (QKD) [1-3], which is much closer to standard optical telecommunication techniques than discrete variable (DV) QKD. In particular, CVQKD does not use photon counters, but coherent (homodyne or heterodyne) detections, which are now very usual in high-speed commercial telecom systems. In addition, using a “truly local” oscillator allows one to simplify security issues, and to eliminate potentially unsecure side channels. We will present recent developments in CVQKD using Probabilistic Constellation Shaping [4], also related to recent security proofs [5,6], and to hardware improvement. This talk will illustrate the potential of CVQKD, and of CV in general, for a widespread use in secure communication networks.

[1] F Grosshans, G V Assche, J Wenger, R Brouri, N J Cerf and P Grangier, Nature 421, 238 (2003)

[2] P Jouguet, S Kunz-Jacques, A Leverrier, P Grangier and E Diamanti, Nat. Photonics 7, 378 (2013)

[3] E Diamanti and A Leverrier, Entropy 17, 6072 (2016)

[4] F Roumestan, A Ghazisaeidi, J Renaudier, P Brindel, E Diamanti, P Grangier, paper F4E.1, OFC 2021.

[5] S Ghorai, P Grangier, E Diamanti, and A Leverrier, Phys. Rev. X 9, 021059 (2019)

[6] A Denys, P Brown, A Leverrier, arXiv:2103.13945 [quant-ph] (2021)### Imaging the First Few Femtoseconds of Freedom in Strong-Field Laser Ionization

#### Phil Bucksbaum

Stanford University, Stanford, CA, USA

phbuck@stanford.edu

##### Abstract:

Strong-field laser ionization of the electrons bound in small molecules is not instantaneous but typically evolves over one to a few cycles of the driving laser field. The complex underlying quantum dynamics is revealed in many ways, through the timing and sequence of multiple ionizations, the angular correlations in dissociation fragments, elaborate electron momentum patterns, and radiation of high harmonics. Each of these data is a type of image of the strong-field ionization process. Taken together, they help create a more complete picture of the first few femtoseconds of freedom for the electron.