Mysterious Dance: New technology enables rapid visualization of quantum entanglement of photons
Tencent Technology News August 23 news, researchers at the University of Ottawa in Canada, in collaboration with Danilo Zia and Fabio Sciarrino of the University of Sapienza in Rome, recently demonstrated a new technology that can display the wave function of two entangled photons (the elementary particles that make up light) in real time. This achievement is expected to accelerate the advancement of quantum technology, improve quantum state characterization, quantum communication, and develop new quantum imaging techniques. The research was published in the latest issue of Nature Photonics.
Taking a pair of shoes as an example, the concept of quantum entanglement can be likened to randomly selecting a shoe. The moment you recognize one shoe, the nature of the other shoe (whether left or right) is immediately recognized, regardless of where it is located in the universe. The problem, however, is that there is inherent uncertainty in the identification process until this moment can be observed in real time and with certainty.
Illustration: a: Coincident image of interference between spontaneous parametric sub-transition (SPDC) and state obtained by a pump beam shaped by a yin-yang symbol. The inset map scales are the same as the main image. b: Reconstruct the amplitude and phase structure of the image printed on the pump
The wave function is a core principle of quantum mechanics, which provides a comprehensive understanding of the quantum states of particles. For example, in the case of a shoe, the shoe's "wave function" can carry information such as left or right, size, and color. More precisely, the wave function enables quantum scientists to predict the likely outcomes of various measurements of quantum entities, such as position, velocity, and more.
This predictive power is very useful, especially in the rapidly evolving field of quantum technology, knowing that the quantum states produced or entered into quantum computers will allow testing the computer itself, thus facilitating the development of quantum technology. In addition, the quantum states used in quantum computing are very complex and involve many entities that may exhibit strong non-local correlations (entanglement).
Understanding the wave function of such a quantum system is a challenging task, which is also known as quantum state tomography or quantum tomography. Using standard methods (based on so-called projection manipulations), a complete tomography scan requires a large number of measurements, which increase rapidly as the complexity (dimension) of the system increases. Previous experiments conducted by the team with this method have shown that characterizing or measuring the high-dimensional quantum state of two entangled photons can take hours or even days. In addition, the quality of the results obtained is highly sensitive to noise and depends on the complexity of the experimental setup.
The projection measurement method of quantum tomography can be thought of as viewing the shadows of high-dimensional objects cast on different walls from independent directions. All researchers can see is shadows, from which they can infer the shape (or state) of the entire object. For example, in a CT scan (computed tomography), the information of a 3D object can be reconstructed from a set of 2D images.
In classical optics, however, there is another way to reconstruct 3D objects. This is called digital holography technology, which is based on recording a single image, called an interferogram, obtained by interfering with the scattered light of an object with a reference light.
The research team that made the latest discovery, led by Ibrahim Karimi, chair of the Canadian Structured Quantum Wave Research Chair, co-director of the Ottawa Institute for Quantum Technologies (NexQT) and associate professor in the School of Science, extended the concept to the case of two photons. Reconstructing a two-photon state requires superimposing it with a known quantum state and then analyzing the spatial distribution of locations where two photons arrive at the same time.
The participants in the study, from left to right, are Dr. Alessio de Erico, Dr. Ibrahim Karimi and Dr. Nazanin Dehegan
Imaging in which two photons arrive at the same time is called resynthesis. These photons may come from a reference source or from an unknown source. Quantum mechanics states that the source of photons cannot be determined, which produces interference images that can be used to reconstruct unknown wave functions. The experiment was made possible by an advanced camera that records events at a resolution of nanoseconds (millionths of a second) on each pixel.
Dr. Alessio D'Errico, a postdoc at the University of Ottawa and one of the paper's co-authors, highlighted the great advantages of this innovative approach. "This method is much faster than previous technologies, taking minutes or seconds instead of days," he said. Importantly, detection time is not affected by system complexity, which solves the long-standing scalability challenge in projection tomography. ”
The impact of this research is not limited to academia, it also has the potential to accelerate advances in quantum technology, such as improved quantum state representation, quantum communication, and the development of new quantum imaging techniques. (Text/Golden Deer)