Abstract Modern optical physics provides means to detect and resolve ultrafast processes on a time scale of tens of attoseconds. The physical interpretation of such measurements, however, remains the focus of heated debate. In its conceptual dimension, this debate reflects fundamental difficulties in defining time in quantum mechanics. En route toward resolving this difficulty, we are led to extend universal uncertainty relations to ultrafast light–matter interactions. Such a generalized uncertainty sets a lower bound on the response time inherent in attosecond electronic dynamics driven by ultrashort laser pulses, dictating a speed limit for next-generation photonic information systems — systems of petahertz optoelectronics.
Abstract Modern optical physics provides means to detect and resolve ultrafast processes on a time scale of tens of attoseconds. The physical interpretation of such measurements, however, remains the focus of heated debate. In its conceptual dimension, this debate reflects fundamental difficulties in defining time in quantum mechanics. En route toward resolving this difficulty, we are led to extend universal uncertainty relations to ultrafast light–matter interactions. Such a generalized uncertainty sets a lower bound on the response time inherent in attosecond electronic dynamics driven by ultrashort laser pulses, dictating a speed limit for next-generation photonic information systems — systems of petahertz optoelectronics.
Modern quantum optics primarily operates in the quasistationary regime, isolated from the intrinsic timescales of ultrafast optical fields. Pushing these boundaries into the femtosecond and attosecond domains is a critical frontier. Here, we generate, shape, and interrogate the quantum state of an ultrafast squeezed light field. Our optical metrology reveals a highly dynamic, time dependent squeezing distribution across individual half cycles of the electric field. Incorporating this intracycle squeezing into strong field simulations demonstrates that the temporal redistribution of quantum uncertainty fundamentally reshapes the quantum strong field physics of high harmonic emission. Furthermore, we achieve attosecond scale control of the squeezed state, visualized through inferred effective Wigner representations. Finally, we show that ultrafast squeezed light encodes its quantum properties into a photoinduced tunneling current within a petahertz phototransistor with subfemtosecond resolution, demonstrating a direct optical electronic quantum coupling. This work lays the foundation for the emerging field of ultrafast quantum optics and unlocks new avenues for high speed quantum communication and photonics.
The past thirty years witnessed rapid developing of strong field physics that leads to the first generation of attosecond (10−18 s) pulses. The duration of available pulses has recently been reduced to less than 100 as, approaching the Kepler period of a classical electron revolving around the nucleus. For the first time, electron motions inside atoms, molecules and solids can be traced, probed and even steered in real time. It pushed the study on ultrafast dynamic processes into a new frontier, giving birth to attosecond physics. The development of attosecond pulses provides unprecedented coherent ultrashort XUV (extreme ultra-violet) of soft X-ray sources that enable imaging the atomic structure and resolving the related quantum dynamics for matter science. In particular, it allows the probing and monitoring of electron dynamics in the natural time scale of attoseconds with atomic spatial resolution. The generation and applications of attosecond pulses are directly related to the control and manipulation of the sub-cycle electron dynamics. Recent studies on the correlated multielectron dynamics have provided insight into the optical and dynamical properties of matter in the perspectives of time, phase and entanglement. It deepens our understanding on some of the fundamental questions, e.g., how the single or multiple photons are absorbed and how short are the quantum processes such as photoionization, tunneling ionization and charge migration. Although currently attosecond pulses are limited by the flux and pulse duration, the combination of attosecond pulses with intense infrared laser pulses paves new ways of controlling and probing electron dynamics in the domains of energy, time and space that lays the foundation for petahertz optoelectronics and attosecond pulse based transient spectroscopy. In this review, we will first briefly summarize the advancement of strong field and ultrafast physics including the relevant experimental findings, the theoretical explorations, the related technologies and the possible applications. Then we focus on the sub-cycle electron or multielectron dynamics and their manifestation on the ionization and coherent radiation properties. We start with the time behavior of Fano resonance and how it can be probed in time domain. In section 2, the correlated electron dynamics is discussed in term of anti-screening effect and Pauli effect that influence strong field ionization and high harmonic generation processes. In section 3, the coherent emission with frequency from terahertz to soft XUV and their joint measurement are discussed by emphasizing the generation mechanism of terahertz wave in two-color laser pulses. The developed high-harmonic and terahertz wave spectroscopy (HATS) is shown capable of imaging the molecular structure and dynamics. In section 4, the time-resolving of electron and hole dynamics and their coherence is proposed based on attosecond transient absorption technique. The coherence of ionization and the correlated electron dynamics is hinted crucial for electron-hole interaction. The topics are very limited and mainly selected from the perspectives of our group.
Advancements in quantum optics and squeezed light generation have revolutionized various fields of quantum science over the past three decades, with notable applications such as gravitational wave detection. Here, we extend the use of squeezed light to the realm of ultrafast quantum science. We demonstrate the generation of the shortest ultrafast synthesized quantum light pulses spanning 0.33 to 0.73 PHz by a degenerate four-wave mixing nonlinear process. Experimental metrology results confirm that these pulses exhibit amplitude squeezing, which is consistent with theoretical predictions. Moreover, we observe the temporal dynamics of amplitude uncertainty of the squeezed light, demonstrating that quantum uncertainty of light is controllable and tunable in real time. Additionally, we demonstrate control over the quantum state of light by switching between amplitude and phase squeezing. Our ability to generate and manipulate ultrafast, squeezed, synthesized light waveforms with attosecond resolution unlocks exciting possibilities for quantum technologies, including petahertz-scale secure quantum communication, quantum computing, and ultrafast spectroscopy. As an example, we introduce an attosecond quantum encryption protocol leveraging squeezed synthesized light for secure digital communication at unprecedented speeds. This work paves the way for exploring quantum uncertainty dynamics and establishes the foundation for the emerging ultrafast and attosecond quantum science fields.
Nonclassical states of light are central resources for quantum metrology and quantum information, yet most high performance squeezing platforms operate in narrowband or continuous-wave regimes where the quantum noise is effectively stationary. This work advances ultrafast quantum optics by demonstrating how squeezed states can be generated, measured, and engineered on femtosecond and attosecond time scales, so that quantum fluctuations become a controllable property of the optical waveform itself. In this work, broadband few-cycle coherent drivers are produced using the light field synthesizer (LFS) setup that coherently combines UV/VIS/NIR channels with independently adjustable delays and amplitudes. Ultrafast squeezed light is generated via degenerate four-wave mixing (DFWM) in fused silica using a three-beam interaction geometry, implemented as a quantum light field squeezer (QLFS) that enables quasi-collinear phase matching across a wide bandwidth. A metrology framework compatible with ultrashort pulses is developed: amplitude (intensity) uncertainty is extracted from shot-to-shot spectral statistics, while relative phase fluctuations are retrieved from spectral-interference fringes in channel-overlap regions. These observables are connected to a displaced squeezed state model by fitting variance expressions, enabling phase-space visualization through Wigner function reconstruction. Beyond static squeezing, the QLFS provides attosecond-resolved control of the generated quantum state by tuning inter-pulse delay and phase matching geometry, allowing the redistribution of uncertainty between conjugate quadratures and revealing time-dependent (sub-cycle) structure of the intensity uncertainty within the optical cycle. Finally, the work extends ultrafast quantum optics into solid-state systems by demonstrating squeezed light driven tunneling in a graphene-silicon-graphene phototransistor, where state-dependent modulation of current noise is observed alongside simultaneous optical uncertainty measurements. Together, these results establish a practical route to waveform-level quantum state engineering and motivate future ultrafast quantum metrology, strong field quantum optics control, and hybrid photonic electronic quantum technologies.
Until recently, attosecond optical spectroscopy and quantum optics evolved along non-overlapping directions. In attosecond science, attosecond pulses have been regarded as classical waves, applied to probe electron dynamics on their natural time scale. Here, we transfer fundamental concepts of quantum optics into attosecond physics, enabling control of both the properties of the XUV attosecond pulses and the quantum fluctuations of matter on attosecond time scales. By combining bright squeezed vacuum (BSV) with a strong laser field to drive high-harmonic generation, we transfer the quantum properties of the BSV onto the resulting XUV attosecond pulses. Applying advanced attosecond interferometry, we reconstruct the quantum state of the XUV high harmonics and their associated attosecond pulses with attosecond precision. Finally, we resolve the squeezing of the electron's wavepacket during one of the most fundamental strong-field phenomena - field induced tunneling. The ability to measure and control quantum correlations in both electrons and XUV attosecond pulses establishes a foundation for attosecond quantum electrodynamics, manipulating the quantum state of electrons and photons with sub-cycle precision.
At the present time suopicosecond pulses of laser light as short as 0.5·10−12 s have been generated and detected and the possssibility of 50·10−15 s pulses generation as a limit is predicted [1]. Nothing has been said about the fundamental physical reasons that determine this limit. The aim of our work is to throw some light upon the generate mechanisms that govern the generation of ultrashort photon pulses and other pulses of physical fields of limited short duration. It is also obvious that the pulse duration Δt cann't be shorter than the elementary time length Δto if if it exists. So let us search for possicis candidates for Δto and look for methods of their generation. There is only one general method availaole to get automatically snortened pluses of boson fields - the method of boson avalanches [2]. It consists of the following: take an excited particle and put it into a physical resonator for a boson field for getting a boson by means of the sneous boson emission process in the resonator in a time τ. If we put N > 1 equel excited particles into the resonator we shall get a pulse of boson radiation consisting of ∼N bosons in a time (τ/N)·η, where η is an interference factor of the order η (λ2/Ao) for a radiating disk of square section Ao and for bosons of wavelength λ. This law was well established for photons generated by solids for which τ = 10−3 s, Ao = 1 cm2, λ2 = 10−10 cm2 and N = 1019 and Δt = 10−12 s. But these numbers are not the limited ones and we could pose for instance N = 1023 and τ = 10−10s. The result Δ t =10−21 will be wrong because in 10−11 s photons can travel only through a distance Δ1 ∼ 3·10−11 cm and a sphere of diameter Δ1 = 3·10−11 led with ordinary matter cann't contain 1023 particies. It must be said that particles outside of this sphere cann't interact to produce a motor, ava-_anche. So we see thatboson avalancnes can generate pulses as shot as needed if the material is as dense as to fulfill the new condition.