/>iAfter building for some time, the excitement surrounding the potential of quantum computing has recently gained momentum. Quantum computing attracted $1.2 billion from venture capitalists in 2023 even as overall investment in technology dropped. Given that quantum computing has yet to perform a real-world use case, why is investment in this area so strong?
A short answer is that quantum computing holds the promise of solving computational problems that are currently intractable. The full answer is a bit more complex.
What is Quantum Computing?
A conventional computer is built from transistors, which represent and manipulate bits of information—logical 1s or 0s. In contrast, a quantum computer is built from physical elements that can store and manipulate quantum bits of information, which are termed “qubits.”
Computation with a quantum computer is similar in many ways to a non-quantum (classical) computer. In a classical computer, you start with values of 0 or 1 for each bit, you apply gates to those bits that manipulate their output to produce new values, and at the end of the process you have a new set of values of 0 or 1 for each bit. In a quantum computer, you similarly start with qubits that each have a value of 0 or 1, you perform gates on those qubits, and at the end, you measure the qubits and measure either a 0 or 1 for each qubit. The important difference is that during computation in a classical computer, every bit is still a 0 or a 1, but in a quantum computer, the qubits can exist in a superposition of 0 and 1 during the computation and can also become entangled with one another such that the value of one qubit depends on the value of another qubit. These strange properties of quantum systems that qubits exhibit mean that there is a huge amount of computational space available to a quantum computer, which can dramatically improve complex calculations. For example, 30 classical bits can always be described by 30 values (i.e., 30 0s or 1s); however, to fully describe a system of 30 qubits you would need around a billion values. A quantum computer won’t be any faster at calculating 2+2=4, but when it comes to complex problems, it will be exponentially faster. As a result, some problems that would take centuries to calculate with classical computers could be performed in seconds.
Recent Developments
Despite significant remaining challenges (discussed below), many companies have shown progress in putting together the building blocks of a quantum computer.
There are several competing types of quantum computing technologies, each using a different strategy to construct these building blocks. For example, some technologies configure small superconducting circuits to have particular controllable states. Other technologies trap single atoms in a laser beam and control the energy of each individual atom to transition the atoms between particular controllable states. The common aspect of each technology is in creating a very small system that has controllable states, wherein the states can be treated like the values of a bit of information. In particular, one state can be treated like a “0” state, and another state can be treated like a “1” state. But because these are states of a quantum system, the system can be manipulated to be in a superposition of the 0 and 1 states, and therefore operated as a quantum bit (qubit).
To date, several different approaches have successfully built a qubit, stored information in the qubit, manipulated that information, and performed operations that will be a necessary part of quantum computation. In terms of the history of conventional computers, the present moment might be compared to the time when the transistor had been invented but not yet made reliably in sufficient numbers and operated together to perform helpful calculations. As such, the promise that quantum computers will continue to develop to the point of performing helpful real-world calculations seems to be within reach. This may have venture capitalists excited for the field’s short-term future.
Challenges, Promise, and Future
There are still significant challenges to overcome in quantum computing. The primary challenge currently facing the field is scaling the successes in building and operating a handful of qubits to thousands or even millions of qubits. Now, the largest quantum computing systems include no more than around 100 qubits. While building that many qubits is a significant achievement, a larger system is needed for practical computation.
A fully realized quantum computer with thousands or millions of controllable qubits should be able to better model complex systems, such as protein folding, material science, drug discovery and chemical processes, and make unprecedented discoveries in those fields. Similarly, financial modeling and machine learning (AI) should be dramatically improved by quantum computation through faster and more accurate predictions.
These improvements would drastically change a number of fields, and companies with access to the most powerful quantum computers would have a huge advantage, as they would be able to discover new drugs, design new materials, improve the efficiency of complex physical processes, or design better AI applications at a faster pace than others.
Investments in quantum computing are incredibly important to continue development of the field and the techniques needed to get to practical computation, though it is unlikely that these will pay off in the short term. But the potential benefits to producing quantum computers that can solve some of these problem is immense.
The cost-benefit of the promise of quantum computers is clear: Despite the uncertainty in producing a quantum computer that can solve useful problems and the expected timeline to do so, the potential upside is significant, and companies should keep a close eye on developments in this field.
