Xanadu Quantum Technologies Ltd. has been on a wild stock market ride since going public three weeks ago. The Toronto company, which went public by merging with a Nasdaq-listed special-purpose acquisition company, saw its share price slide after its strong trading debut on March 27. It closed that day at US$11.50 but ended last Thursday at US$7.65. Since then, the stock has been on an exponential tear, appreciating in value by increasingly higher double-digit percentages each day. The stock closed up 17.1 per cent last Friday, 28.2 per cent on Monday, 29 per cent on Tuesday and 70 per cent on Wednesday, ending at US$25.18. Xanadu, which is also listed on the Toronto Stock Exchange, appreciated so rapidly late Wednesday morning that it triggered a temporary trading halt on the Canadian exchange for a few minutes. That made Xanadu Canada’s fifth-most valuable publicly traded technology company, with a market capitalization of US$7.5-billion. Founder and chief executive officer Christian Weedbrook, who has 46.4 million multiple voting shares, is now a billionaire, though he has said he doesn’t pay much attention to the stock price. Much of this week’s gains happened after chip behemoth Nvidia Corp. said Tuesday that its new open-source family of artificial intelligence models, called Ising, will enable researchers and businesses to speed up the performance and accuracy of the decoding process needed to correct errors that are part of the process of quantum computing operations. Reducing errors is a key challenge all quantum computer developers must solve before their machines can operate at full scale. Nvidia’s news pushed up stocks of all quantum computer companies, including B.C.-founded D-Wave Quantum Inc. Other Xanadu backers are sitting on paper windfalls. The Ontario Municipal Employees Retirement System pension fund – one of the first investors in Xanadu and an early backer