Though the initial burst of activity has slowed, some experts say the explosion in commerce showed just how capitalist Cubans were all along. Of the roughly 350,000 people licensed to be self-employed under the new laws by the end of 2011, 67 percent had no prior job affiliation listed — which most likely means they were running underground businesses that then became legitimate.

Some of the most successful entrepreneurs are optimistic about Cuba’s becoming more open to free market ideas. Héctor Higuera Martínez, 39, the owner of Le Chansonnier, one of Havana’s finest restaurants (the duck is practically Parisian), says that officials are “starting to realize there is a reason to support private businesses.” He has given people work, for example, and he brings in hard currency from foreigners, including Americans.

“Before, we had nothing,” he said. “Now we have an opportunity.”

He is doing everything he can to make the most of it. When we met one night at the restaurant, he had already written up several pages of notes and charts explaining what his industry needed to grow — from wholesale markets to improved transportation for farmers to an end to the American trade embargo to changes in the Cuban tax code. In an ingeniously cobbled-together kitchen, in which only one of three ovens worked, he mostly seemed to salivate at the thought of vacuum packing so his meals could be delivered more efficiently.

HE was about as capitalist as it gets. But will his ideas ever be adopted? Like everyone else, he faces severe limits. He can hire no more than 20 employees, for example. He does not have access to private bank loans, and the government has shown little inclination to let people like Mr. Higuera succeed on a grand scale.

Instead, when success arrives, the government seems to get nervous. This past summer, officials shut down a thriving restaurant and cabaret featuring opera and dance in what had been a vacant lot, charging the owner with “personal enrichment” because he charged a $2 cover at the door. A news article from Reuters had described it as Cuba’s largest private business. A few days later, it was gone, along with 130 jobs.

The Castro government has tried to keep a lid on innovation in other ways, too. It has not allowed professionals like lawyers and architects to work for themselves. And its efforts at political repression have focused over the past few years on innovative young people seeking space for civil discourse in public and online — the blogger Yoani Sánchez, or Antonio Rodiles, director of an independent project called Estado de Sats, who was arrested in early November and released last week after 18 days in jail.