Quantum computing is the lovechild of quantum physics and computer science. In this talk we look at what quantum computation is, why physicists, chemists and computer scientists might want to do it, and where we are today. There are many possible physical architectures for realising a quantum computer, we will focus on optical quantum computing, where the information is encoded and manipulated using single photons. Formany years this was thought to be science-fiction, but with the discovery of measurement-induced nonlinearity there has been an explosion of interest world-wide, and a slew of ”firsts” in demonstration systems. Scaling up from these small systems to a large error-free computer is possible in principle: at first it was thought it would take horrific numbers of ”physical” gates per ”logical” gate. Recently proposed schemes reduce these overhead requirements from the order of 10,000 to 50, and possibly even 1 - great news if you’re an experimentalist! Finally, we will look briefly at some of the scientific and technological challenges ahead, and present our latest experimental results where we build a small optical quantum system for quantum chemistry, calculating the properties of molecular hydrogen to an accuracy of 20 bits.
Quantum computing is the lovechild of quantum physics and computer science. In this talk we look at what quantum computation is, why physicists, chemists and computer scientists might want to do it, and where we are today. There are many possible physical architectures for realising a quantum computer, we will focus on optical quantum computing, where the information is encoded and manipulated using single photons. Formany years this was thought to be science-fiction, but with the discovery of measurement-induced nonlinearity there has been an explosion of interest world-wide, and a slew of ”firsts” in demonstration systems. Scaling up from these small systems to a large error-free computer is possible in principle: at first it was thought it would take horrific numbers of ”physical” gates per ”logical” gate. Recently proposed schemes reduce these overhead requirements from the order of 10,000 to 50, and possibly even 1 - great news if you’re an experimentalist! Finally, we will look briefly at some of the scientific and technological challenges ahead, and present our latest experimental results where we build a small optical quantum system for quantum chemistry, calculating the properties of molecular hydrogen to an accuracy of 20 bits.
In 2001, all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single-photon sources, linear optical elements, and single-photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high-efficiency single-photon detectors, and low-loss interfacing of these components.
We are on the verge of a new era in computation, one that operates on the strange and wonderful rules of the quantum world. This article explores the story of quantum computing, a technology that promises to solve problems far beyond the reach of today's fastest supercomputers. We'll journey from the core ideas that make it all possible—concepts like superposition and entanglement—to the incredible machines being built in labs around the world. We'll see how these machines are being programmed and witness the first hints of their power in fields like medicine, materials science, and cybersecurity. Finally, we'll take an honest look at the immense challenges that still lie ahead on the path to building a truly powerful quantum computer. This is a story of human ingenuity pushing the boundaries of science, a tale of the immense potential and practical hurdles of the coming quantum age.
In this research notebook on quantum computation and applications for quantum engineers, researchers, and scientists, we will discuss and summarized the core principles and practical application areas of quantum computation. We first discuss the historical prospect from which quantum computing emerged from the early days of computing before the dominance of modern microprocessors. And the re-emergence of that quest with the sunset of Moore's law in the current decade. The mapping of computation onto the behavior of physical systems is a historical challenge vividly illustrate by considering how quantum bits may be realized with a wide variety of physical systems, spanning from atoms to photons, using semiconductors and superconductors. The computing algorithms also change with the underline variety of physical systems and the possibility of encoding the information in the quantum systems compared to the ordinary classical computers because of these new abilities afforded by quantum systems. We will also consider the emerging engineering, science, technology, business, and social implications of these advancements. We will describe a substantial difference between quantum and classical computation paradigm. After we will discuss and understand engineering challenges currently faced by developers of the real quantum computation system. We will evaluate the essential technology required for quantum computers to be able to function correctly. Later on, discuss the potential business application, which can be touch by these new computation capabilities. We utilize the IBM Quantum Experience to run the real-world problem, although on a small scale.
A broad effort is currently underway to develop quantum computers that can outperform classical counterparts for certain computational or simulation tasks. Suppressing errors is one of the central challenges for useful quantum computing, requiring quantum error correction for large-scale processing. However, the overhead in the realization of error-corrected “logical” qubits, where information is encoded across many physical qubits for redundancy, poses significant challenges to large-scale logical quantum computing. In this talk, we will discuss the recent advances involving programmable, coherent manipulation of quantum systems based on neutral atom arrays excited into Rydberg states, allowing the control over several hundred qubits in two dimensions. Optical control techniques are central to this approach. In particular, we use this platform to explore quantum algorithms with encoded logical qubits and quantum error correction techniques. Using this logical processor with various types of error-correcting codes, we demonstrate that we can improve logical two-qubit gates by increasing code size, outperform physical qubit fidelities, create logical GHZ states, and perform computationally complex scrambling circuits using 48 logical qubits and hundreds of logical gates. These results herald the advent of early error-corrected quantum computation, enabling new applications and inspiring a shift in addressing both the challenges and opportunities that lay ahead.
Quantum Computing often described as one of the most exciting frontiers of modern science—a field that does not just push the boundaries of technology but also reshapes how we think about solving problems. Unlike classical computers, which process information in simple 0s and 1s, quantum mechanics, allowing a single qubit to explore multiple possibilities at the same time. This gives them the potential to perform calculations that would take even today’s most powerful supercomputers thousands of years. In recent years, progress has been rapid, with breakthroughs in hardware, algorithms and applications that range from developing new medicines to strengthening artificial intelligence and tackling climate change. Yet, enormous challenges remain, such as stabilizing fragile qubits, reducing error rates, and making these systems accessible beyond a handful of elite labs. This paper explores both the promises and the pitfalls of quantum computing, offering a closer look at how it could reshape industries, global security and even the pace of human innovation in the decades ahead.
To advance quantum information science and technologies, a wide variety of quantum machines and protocols are being developed based on different physical systems. Interconnecting these systems is a grand challenge to scale up quantum information architectures. This effort requires to develop specialized photonic devices and capabilities, ranging from efficient photon extraction for qubit connectivity to the implementation of advanced optical memories. In this talk, I will provide an overview of the opportunities presented by networking, including long-distance quantum communication and distributed quantum computing. I will also present our recent experimental demonstrations, which enable the realization of a quantum-bit-encoding converter, the implementation and use of highly-efficient quantum memories based on laser-cooled neutral atoms, and the development of nanophotonic devices for qubit coupling.