How Close Are We—Really—to Building a Quantum Computer?
The development of a quantum computer, capable of revolutionizing fields such as materials science, data encryption, and climate prediction, is a race among major tech companies like IBM, Microsoft, Google, and Intel. While a fully functional quantum computer is still more than a decade away, these companies celebrate incremental advancements in packing more quantum bits, or qubits, onto a processor chip. However, the path to quantum computing involves much more than manipulating subatomic particles.
A qubit can represent both 0 and 1 simultaneously due to a quantum property known as superposition. This property allows qubits to perform multiple calculations simultaneously, significantly increasing computing speed and capacity. However, not all qubits are the same, and there are various types with different characteristics. For example, in a spin qubit, the state of the bit depends on the direction its electron is spinning. Despite their potential, qubits are notoriously fragile and require extremely low temperatures, around 20 millikelvins, to remain stable.
Building a quantum computer involves more than just the processor. These systems will require new algorithms, software, interconnects, and other yet-to-be-invented technologies to take full advantage of their processing power and enable data sharing and storage. Intel, for instance, introduced a 49-qubit processor called Tangle Lake and created a virtual-testing environment using a supercomputer to simulate up to a 42-qubit processor. However, to develop software for quantum computers, researchers need to simulate hundreds or even thousands of qubits.
In an interview, Director of Quantum Hardware at Intel Labs, Jim Clarke, discusses the different approaches to building a quantum computer, the fragility of qubits, and the challenges in the field. He explains that quantum computing allows for exponential state space and uses the example of coins to illustrate the concept. Unlike classical bits, which are either 0 or 1, qubits in superposition can represent multiple states simultaneously. However, qubits eventually collapse into a particular state due to factors like noise, temperature changes, or vibrations. To stabilize qubits, they are kept at extremely low temperatures using a dilution refrigerator.
There are various types of qubits, including superconducting systems, trapped ions, and silicon spin qubits. Different types manipulate and communicate with qubits in unique ways. Intel is studying silicon spin qubits, which resemble conventional silicon transistors but use a single electron to operate. Although less mature than superconducting qubits, spin qubits have potential for scalability and commercialization.
The path to building a quantum computer involves developing quantum chips, building simulators, and improving qubit quality. Simulators help in developing architecture, compilers, and algorithms, but physical systems with a few hundred to a thousand qubits are needed to determine the software and applications that can run on them. The challenge lies in scaling up the system by adding more qubits, which requires more physical space, or by shrinking the inner dimensions of the integrated circuit. Intel is studying spin qubits as a potentially smaller alternative.
Regarding the impact of quantum computing, governments worldwide are investing in the technology. Lawmakers are exploring national strategies, standards, and workforce development to ensure their countries remain competitive. Quantum computing has potential applications in security, chemistry, materials modeling, and even artificial intelligence (AI). While AI development will likely be driven by conventional chips optimized for AI algorithms, quantum computing can contribute to AI research and applications.
In terms of a timeline for working quantum computers, historical advancements like the first transistor and integrated circuit took more than a decade between each milestone. Quantum computers are not just around the corner, and the complexity of the technology suggests that it will take time to achieve significant breakthroughs. If a quantum computer with a few thousand qubits becomes a reality in the next 10 years, it could have a transformative impact comparable to the introduction of the first microprocessor. Despite optimistic claims of a three-year timeframe, the understanding of the complexity of quantum technology suggests a longer path ahead.