IonQ (NYSE: IONQ) has been a divisive stock ever since its public debut in October 2021. The bulls were dazzled by the quantum computing company's growing list of contracts and bold claims of miniaturizing quantum processing units (QPUs), but the bears were skeptical about its ambitious growth plans.

IonQ's stock opened at $10.60 on the first day after it went public by merging with a special purpose acquisition company (SPAC). It soared as high as $31 a month later, but it dropped to about $3 by December 2022. But today, it trades at about $41 -- so investors who scooped it up at its all-time low have netted some big gains in just two years. Can IonQ maintain that momentum and become a massive quantum computing leader over the next decade?

To understand why IonQ is such a divisive stock, we should first understand how quantum computing works. Traditional computers still store zeros and ones as binary bits of data, but quantum computers can store zeros and ones simultaneously in quantum bits (qubits). As a result, quantum computers can process massive amounts of data at a much faster rate than traditional binary computers. However, quantum computers are also much larger, more expensive, and make more computing errors -- so they're still mainly used by large government agencies and research institutions for niche tasks.

IonQ sells three main quantum computers: its top-tier Aria system, its commercial Forte system, and its on-premise Forte Enterprise system. It also provides its own quantum computing power as a cloud-based service. It sells these systems to the U.S. Air Force Research Lab, other government agencies, and major universities.

IonQ generates steady revenue from those customers, but it got a lot of buzz by claiming it could shrink the width of existing QPUs from a few feet to a few inches with its proprietary "trapped ion" technology. It claimed that process would support the production of smaller, cheaper, and less error-prone quantum computers. But like many SPAC-backed start-ups, IonQ overpromised and underdelivered. Here's how broadly it missed its own growth expectations from 2021 to 2023.

Data source: IonQ.

As IonQ missed its own pre-merger estimates, rising interest rates highlighted its losses and crushed its valuations. It also suffered a major setback in late 2023 when its co-founder and Chief Science Officer Chris Monroe, who had pioneered its entire "trapped ion" process, abruptly stepped down to return to "academic, research and policy pursuits."